Tumblr is getting into video chatting today with a new app called Cabana. The app lets up to six people video chat at the same time, but with a twist: Cabana isn’t about just getting together to talk, it’s about getting together to watch YouTube videos.

After joining a Cabana chat, anyone in the room will be able to browse through YouTube and select a video. It’ll start playing for everyone in the room, and the idea is that you’ll all be able to watch it together, enjoying each others’ silence or chatting over the entire thing.

“When I saw [the app for the first time], I said, ‘Shit, I can't believe you actually can't do this yet,’” says Tumblr founder and CEO David Karp. “Yeah, you can hang out with your buddies in a group chat, yeah you can send somebody a link to a video. But that experience of getting to sit there there and watch [a video] with them as they watch it for the first time, that just didn't exist yet.”

Karp’s hope is that people will use Cabana to introduce their friends to “that ridiculous or amazing or totally insightful incredible video” they’ve just found. It’s supposed to replicate that experience of being in a room together, pulling up a favorite YouTube video, and watching everyone’s reaction before starting on another.

Cabana isn’t connected to Tumblr at all — it’s a new social graph

Cabana is a particularly interesting bet for Tumblr because it’s so unlike Tumblr itself. Where Tumblr is organized around strangers with shared interests, Cabana is all about bringing together close friends who actually know each other. At launch, Cabana isn’t even linked to Tumblr — you’ll have to find your friends all over again by looking up their phone numbers.

The app offers Tumblr an opportunity to expand its reach by connecting people in a very different way than it does today. That may be an important goal for the company: the research firm eMarketer pegs Tumblr’s US users at around 23 million — a third as many as Instagram, which launched three years later. The firm believes Tumblr’s user growth is slowing, which isn’t a great sign for a once explosive network.

For the most part, Karp says this isn’t what Tumblr is after with Cabana. “I mean sure, we're always looking at everything we launch as an opportunity to reach more people, be meaningful to more people,” he says. But Karp adds that the company’s focus remains on Tumblr, suggesting we won’t see more and more standalone apps. “I don’t know that it's part of a bigger strategic direction or push,” he says of Cabana.

Though Tumblr is launching this app and has been involved in its development, Cabana didn’t originate inside the company. The app started in a Yahoo incubator and caught Karp’s interest after he saw a demo. Then in the past couple months, it was brought under Tumblr’s umbrella. Karp wouldn’t say whether Cabana and Tumblr would integrate at any point.

Developers have tried and failed at group video chatting countless times, but there’s at least some reason to think Cabana may be on to something. For one, it has Tumblr’s backing and will get plenty of promotion. And the app is also built with many of the same mechanics used by Houseparty, the group video chatting app launched by the company behind Meerkat, which has seen some early success.

Like Houseparty, Cabana immediately launches users into their own broadcast, and it’ll alert all their friends with a push notification. It’s designed to let people easily jump in and out of chats, making video chatting a lot more casual than it’s long been on the web. Houseparty hit a million users within a year, making it something of a surprise hit.

“The blend of hanging out and watching in Cabana is actually super hard to accomplish.”

But that also brings up another issue: what can Cabana do to stand out, if a YouTube integration is its only unique feature?

Jason Lee, the current head of Cabana, says not to count on the app’s core twist being cloned right away. “The blend of hanging out and watching in Cabana is actually super hard to accomplish,” he says. “One interesting thing we spent a lot of time on is making sure audio is balanced between in chat and hanging out.” Lee also says the new features planned for Cabana should keep the app distinct from its competitors.

For now, it sounds like those features will all revolve around watching, rather than Cabana expanding into other areas, like games. The app only integrates with YouTube for now — using YouTube’s open extensions; there’s no partnership — and Lee wouldn’t say what’ll get added next. It’s easy to imagine Netflix being the dream integration here, but it’s not clear that a controlling service like Netflix would be interested or even able to make such a commitment.

Cabana launches on iOS today in the United States and will come to Android in a few weeks. Karp sees the app as something anyone can use, but Lee says he expects it to connect most with teenagers and young adults.

There’s no question that Cabana taps into a real social interaction that doesn’t quite exist online. And while Tumblr isn’t focusing on it, Cabana sounds like it’d be good for listening to music with friends, too.

But as someone outside the target age range, I already know I’m going to stay far away. Because as the webcomic XKCD illustrated years ago, this is what all parties turn into once someone opens up YouTube: