Earlier this year, my 5-year-old cousin sat down next to me with her mom’s iPhone to watch some of her favorite videos on YouTube. The first thing she pulled up wasn’t a clip from her favorite TV show or a sing-a-long video, though; it was an unboxing video, one that showed adult hands playing with a set of miniature Japanese cooking toys, demonstrating how they could be played with in complete silence. Kelsey doesn’t know what ramen noodles are (she said, “look, pasta!”) but she’s eager to watch strange adults online play with toys she doesn’t have access to.

Unboxing videos, especially of new technology, have been growing in popularity for the past few years—between 2013 and 2014, views of unboxing videos grew 57 percent, garnering a total of 1 billion views in 2014 alone, according to Google’s research team. And according to the video marketing consultants at TubularInsights, videos with the word “unboxing” in the title get an average of 10,000 views. YouTube channels specifically devoted to unboxing toys are particularly popular.

Take Ryan’s Toy Reviews, for example. The channel, which features videos of 4-year-old Ryan unboxing and playing with toys, launched in 2015 and now has more than 5.4 million followers. By late November 2016, it topped the YouTube charts in popularity, receiving more views than any other channel—182.6 million in just a week—for the 15th week in a row. Ryan is even more popular than Justin Bieber.

But Ryan, who is about the same age as his intended audience, is not the typical demographic represented in the stars of these videos. Instead, many of the people unwrapping and playing with toys on YouTube—voicing Barbies, Peppa Pig toys, Spongebob figures, and more—are adults.

These channels aren’t some obscure trend hidden in random corners of the Internet. One, Fun Toys Collector, has more than 8.5 million subscribers and 12.1 billion views. The videos almost always feature adult voices—typically female, high-pitched, insanely enthusiastic, and a little whispery—giving voice to toy characters, their hands occasionally popping out from behind the camera to manipulate the dolls and other toys. Usually at least some of the toys are unboxed on-camera before they’re played with.

A favorite channel among both my cousins and other pint-sized mental_floss friends is the saccharine CookieSwirlC, which has nearly 3.7 million subscribers. Since its inception in late 2013, it’s gathered more than 4.2 billion views in total. According to her site, “CookieSwirlC is a collector of many toys including Shopkins, Barbie and Build-a-Bear,” and she started her channel “to share her passion of toys and creating stories through play.” She doesn’t take money from toy companies in exchange for coverage, and says on her site that she only features toys she herself collects. This isn’t her only channel. The creator, who did not respond to multiple interview requests, started her toy-reviewing career with a channel focused on model horses, from Breyer figures to My Little Pony toys. She goes by the pseudonym Cookie on the CookieSwirlC site, but on her horse-focused blog, HoneyHeartsC, she refers to herself as Honey.

Like many toy accounts, HoneyHeartsC—which has significantly fewer followers than her general toy channel, about 205,700 subscribers—blends playing with dolls and horses with unboxing and reviewing the toys. In one typical video, two Barbies talk about how one of them dances with her horse—and cue the detailed description and unboxing of a “Barbie Dancing Fun Horse” toy. The narration sounds genuinely enthusiastic, like a kid opening presents on Christmas morning. The camera focuses lovingly on tiny details of the box. Sometimes the pictures depicting how the toy can be played with are narrated as if part of a playtime story, too. The narrator dissects the colors of the Barbies’ hair, the brushability of the horses’ tails, the accessories, and more, interspersing directions for using the toys (how to place the Barbies on the horses, how to get the horse toys to walk) and imaginative play plots, like one in which one Barbie is anxious to catch up to the other rider, for instance. You sometimes see the creator’s hands—pink sparkly nail polish and all—but for the most part, the camera is angled to make the toys look like they move on their own.

For Nathalie Clark, 30, and Mercy Casiano, 29, who jointly run the 1.3-million-subscriber channel Toys Unlimited, the choice to start playing with toys on the Internet was an easy business decision. The two met as nurses working in Houston, and started their channel a year and a half ago when Nathalie spotted a story on Facebook about one toy collector’s wildly popular YouTube channel. “I was like, ‘we can do this,’” Clark tells mental_floss. Now, thanks to YouTube’s monetization option, Casiano has quit her job to work on the channel full-time, and Nathalie works only a few days a month.

Though plenty of YouTubers in the toy world are avid collectors, Clark and Casiano, who go by the nicknames Nat and Essie in their videos, are all business. Clark has a 5-month-old who’s too young to appreciate their videos, and Casiano doesn’t have kids. Casiano says that while people assume they must love toys in real life, “That’s not the case in my situation. It was really just an opportunity.” It’s not hard to see how playing with toys on camera might be a preferable job to putting in long, stressful hours at a hospital. While they like being their own bosses, Clark and Casiano also feel like it’s a philanthropic endeavor: The pair donates the toys they buy or receive for the videos to pediatric hospitals in both Houston and in the Philippines, where Mercy went to nursing school.

Unfortunately, the realities of making YouTube your full-time job aren’t as glamorous as they might sound. “If you want to become a YouTuber, it’s extremely competitive,” Casiano explains. “You have to put out at least one video every day. I feel like it’s more of a quantity over putting the best quality you can.” Instead of nursing, the duo works 10-hour days, six days a week, to meet their goal of posting at least one video of each of them unboxing and playing with toys per day. They typically post around 14 to 16 videos total each week.

The extreme competition for clicks might be why I found YouTubers so hard to track down. Of the multiple emails I sent out to 15 different YouTube creators, many of whom have millions of followers, I received only two responses (aside from one that came in an unusable form of broken English). Apparently, many toy YouTubers are either loath to talk about their job or exceedingly busy, and based on the people I was able to track down, the latter feels like a legitimate excuse. It’s hard to find time for an interview when you can’t even take a full weekend off.

But it’s still a pretty good business, if your channel is popular enough. With a little help from Google Translate and the basic Spanish I learned in high school, I emailed with Javier Pombo, a 32-year-old in A Caruña, Spain who runs a channel called Toys & Games. It initially started out as an unboxing channel for Kinder Surprise eggs, then morphed into a toy channel when he and his brother discovered exactly how popular Peppa Pig channels were getting. Though Toys & Games is relatively small with only 143,000 followers, Pombo's six-channel operation, Nano Studios, now has three other employees—all women between the ages of 20 and 25—who come up with the ideas for the episodes and play with the toys on camera. Right now, they create around 15 videos every week, translating their Spanish videos into English (with a freelance English-language narrator) so they can appeal to a wider audience. Like Toys Unlimited’s creators, Nano Studios, which runs another toy channel called Funny Stories for Children, buys most of the toys on display, though some come from the Spanish toy company Bandai España and the New Jersey-based Calico Critters. The business is successful enough that Pombo plans to add another two channels to the roster in early 2017.

These videos aren’t promoting particularly under-the-radar toys, no doubt due to both the promotional toys companies send in and the need to compete for kids’ clicks. To find the trendiest toys to feature on their channel, Casiano and Clark watch the Disney Channel to note what's new and popular and survey all their friends who have kids about the latest "in" toys and shows. If a video doesn’t feature a Disney character, it’s a Barbie, or a My Little Pony figure, or a Peppa Pig toy. Unsurprisingly, many channels capitalize on the intense popularity of the 2013 movie Frozen, to the point where seeing a clip that doesn’t involve one of the Frozen princesses is a rarity.

For instance, Come Play With Me, a channel with more than 992,000 followers that seems to involve actual children playing—or at least hires people with extremely child-like voices—almost exclusively traffics in playing with Anna and Elsa figures, even in videos that include characters from other movies, like Ursula from 1989's The Little Mermaid.

Many of these channels call their videos parodies—perhaps to get around the fact that they’re making money by using trademarked characters—but there’s nothing especially humorous or satirical about them. Most don’t even seem to attempt to be funny. The videos come off as sincere attempts to create the kind of plots a kid would come up with after a visit to the toy box, and some rival the lengths of the shows they’re based on.

Though toy videos on YouTube might look basically like the same thing kids do when they’re playing on their own, not all playtime is the same. Playtime for kids is more than just a fun activity; it helps them develop and practice essential skills they’ll use later in life. Some researchers hypothesize that when kids imagine and play in worlds of their own, with toys or without, it influences the development of creativity, intelligence, and what’s called theory of the mind (understanding that others have desires and perspectives that are separate from yours).

The scientific jury is still out as to whether imaginative play actually causes kids to become more creative or intelligent, but it’s certainly correlated. It’s possible that pretend play just happens to coincide with those developments, and it may be that either kids who are creative and understand other perspectives enjoy playing more, and therefore do it more, or that there’s some third factor that influences both play and creativity at the same time. However, there are a few ways that playing might help kids develop important life skills.

“Imaginary play could encourage social development because children are simultaneously behaving as themselves and as someone else,” as Tracy Gleason—a professor of psychology at Wellesley College in Massachusetts who focuses on the relationships between children and their imaginary friends—writes in an article on The Conversation. “This gives them a chance to explore the world from different perspectives, and is a feat that requires thinking about two ways of being at once, something that children may have difficulty doing in other circumstances."

In other words, it’s good practice for a lot of real-world social situations. “It’s this level of abstraction,” Gleason told me over the phone. “You’re pretending that Barbie is talking and doing things, and you have to think about Barbie’s thoughts and feelings and behaviors. All of that is the kind of thing we do when we empathize with other people.”

The differences between playing and watching aren’t hard to tell when you talk to kids like my cousins. Kelsey, the 5-year-old whose favorite YouTube channel is CookieSwirlC, says she likes toy videos more than playing on her own because “they come up with better stories,” and she likes watching these amateur YouTube videos more than professionally created cartoons. If the YouTube video isn’t in English, she just turns the sound off and watches in silence. Sometimes she and her 8-year-old sister even watch videos featuring toys they have. When they watch YouTube with their little brother, who is about to turn 3, they’ll often watch superhero videos that contain some of the same toys he already owns.

It’s not exactly an imaginative process watching someone else at play, especially when a lot of the content isn’t terribly high quality. Like with a movie, you don’t have to imagine anything, because the story is all laid out for you. But few kids are going to give up playing on their own for YouTube. Riley, Kelsey’s 8-year-old sister, likes to play with her actual toys as much as watch videos of other people playing, even though she likes the different voices YouTubers come up with better than her own. Perhaps because she’s a bit older than her sister, when the videos don’t have an audio track or if the narration is in a different language, she proceeds to make up her own narration, an imaginative endeavor in itself.

Casiano argues that by watching her play on YouTube, kids can be inspired to play themselves. “It helps kids take the toys they have and start creating a story and having their [own] imagination.” She thinks part of the appeal to parents might be that, since as much as 80 percent of their traffic comes from mobile, people are handing their iPads to kids at restaurants or whenever they need a minute of quiet. Then the kids can pretend they’re playing with an infinite number of toys, rather than messing around with the one toy they brought all through dinner.

Now, kids have been coming up with their own imaginative play stories for millennia, so it's pretty strange to think that youngsters need an extra push to play with their toys or come up with creative scenarios in which they're pirates or space aliens or Dr. Barbie. You could argue that in an era when kids are often quieted with iPads and smartphones, anyway, toy videos might spark a little more desire to go off into real, solo imaginative play than say, another Peppa Pig episode. But that's probably not the case, according to experts.

"If you want play to be important, they should be playing," says Kathy Hirsh-Pasek, a psychology professor at Temple University and a senior fellow at the Brookings Institution who studies play and childhood development.

It might not even be the toys in these videos that are attracting kids, for one thing. There's a chance that it's the bright screen itself. “The high resolution and the movement quality [of screens are] something that we know young kids are attracted to,” Hirsh-Pasek says. “I don’t think it has to be a toy. I think frankly it could be anything. I bet they’d be glued to a weather map.” She likens YouTube videos without an educational component to junk food: "We would never substitute our kids meals with cake and candy realistically everything in the right proportions is fine sometimes."

But while watching other people act out relatively boring Barbie plots seems like a pretty weird pastime for the next generation of kids, it’s probably not frying their brains completely. Gleason says that watching toy videos probably isn’t any different from a developmental perspective than any other media. “You’re watching a story unfold,” just like in a cartoon or television show. But from a developmental perspective, it’s actually better for a kid to watch with an adult. “One of the things that’s been demonstrated in the literature is that kids do a lot more processing if someone is watching with them,” Gleason says. “Otherwise it’s very passive.”

It won’t necessarily ruin your child's development to let them entertain themselves with this kind of YouTube Kids content, even if it’s kind of brain candy. It’s not that different from sitting them down in front of the TV. As Gleason puts it, “It’s not necessarily a bad thing, but what else could they be doing that might be more fun and more beneficial to them?” Playing with their own Elsa and Anna toys, probably.