This post originally appeared in Business Insider.

Derek Muller, the curator of science video blog Veritasium, has a pretty large following across a number of social media channels: 21,000 Twitter followers, more than 1 million YouTube subscribers, and 118,000 Facebook fans. But unlike Twitter and YouTube—where his content is not filtered—his Facebook fans who have “liked” his page only ever see a fraction of what he posts.

“The problem with Facebook is that it’s keeping things from you,” says Muller in a new video. “You don’t see most of what’s posted by your friends or the pages you follow.”

Muller is among many page owners who have seen the reach of their pages wane over time. Edge Rank Checker recently analyzed roughly 1,000 different Facebook pages and found another drop in December of the number of people seeing posts, noting that “the News Feed continues to be a more challenging place to get your content displayed.”

So what’s the deal? With so many posts being shared throughout the day on Facebook, Muller says that “clearly some filtering is required. The problem is Facebook is using its filtering power in order to make money.”

Facebook has repeatedly denied any allegations of “throttling” certain posts or “gaming” its news feed against certain pages. “Where he does have a point is that even in the competition for organic news … there’s just a lot more competition than there used to be,” said Facebook spokesman Brandon McCormick.

While McCormick admits that Facebook does “curate the experience,” he strongly rejects the argument that Facebook is forcing people to pay for more exposure. Further, he explained that sponsored posts in the Newsfeed don’t compete with organic posts. They are their own separate, dedicated advertising slots.

“We give users a lot of control over what they see in their News Feed,” McCormick said. “You can filter the News Feed and see everything. You can highlight pages you want to see everything from … a lot of users may not realize that, but anyone can do those things.”

Muller’s argument stems from problems with his own page, Veritasium, of which 118,000 people have become fans. “The last time I shared a video on there, it only went in the news feeds of about 9,000 people,” he claims, a number that is less than 8 percent of his fan base. “This continues the downward trend in numbers I’ve been seeing.”

In part, Muller’s problem is that many of his posts probably aren’t interesting enough to deserve a wider audience. Facebook’s News Feed algorithm is designed to restrict the reach of posts that get little reaction from friends and followers, but to promote posts that get high levels of engagement. It’s been this way for months. Most recently, Facebook tweaked the algorithm to bury pictures of cute cats and surface useful news items.

Facebook advises page owners to produce more “engaging content”—posts and pictures that get likes, comments, and shares. “It doesn’t mean every single person who’s connected is going to see it, but the more engaging content the more people are going to see it,” said McCormick.

With so much content appearing throughout the day, it seems those likes and shares have a huge impact on whether a post gets seen. “Don’t you think it’s possible to see a post and like it or find it interesting without finding a need to ‘like it’ or comment on it?” asks Muller in his video.

“He’s not wrong, but in the absence of another signal that you like that or you’re interested in that type of content,” McCormick said, “it’s hard for us to know.”

The other option, McCormick says, is that he can pay to get his content in front of more people. Muller could increase his reach in the form of promoting posts—paying Facebook anywhere from $50 to thousands of dollars—to ensure they get in front of the page’s fans. That’s much easier for a large brand to do, but far too costly for someone running a small website or nonprofit.

Contrast that with a site like YouTube, where practically anyone with a video camera can make a video, upload it freely to the site, and be paid for it if it gets viewed by many others. On the flip side is Facebook, where people are still creating content, but instead of getting paid for it, they sometimes need to pay to have it viewed.

“On YouTube the roles of creator, advertiser, and viewer are distinct,” Muller says. “The creators make the videos that the viewers want to watch, the advertisers make the pre-rolls and the banner ads, and the majority of viewers are not also creators.”

But that model is nowhere close to Facebook. Muller explains: “The creators are treated like advertisers—they have to pay to reach the viewers. And viewers themselves are also creators. So viewers are also advertisers.”

Of course, if your YouTube video isn’t interesting it meets the same fate as a dull Facebook post: no one sees it, and no one knows it’s there. The difference between the two is that on Facebook you can pay to promote material, whereas on YouTube there’s not much you can do—short of buying an ad campaign across Google—to promote videos.

“[On Twitter,] you just see what you see as you scroll down,” said McCormick. “There’s a big chunk of things you don’t see, that’s the reality of how all services work, unless you spend your entire day scrolling down. Every company is going to have a way to organize this information. No user is ever going to be able to see everything.”

Since Facebook did once offer a high level of reach for free, people feel aggrieved now that it’s been taken away. McCormick compares the changes to search, where in the past you could create a website and easily use search engine optimization to get it seen in the top results. That changes every time Google or Microsoft makes a change to their search algorithm—forcing people to work harder at producing better content that people want to see, or paying for ads.

Still, Muller is not alone in his criticism. A widely shared October 2012 post from the blog Dangerous Minds called it the “greatest ‘bait n’ switch’ in history.” Ironically, Muller posted his video to his Facebook page and it received much higher levels of engagement than what he normally receives—likely due to the large number of likes and shares. Many commenting agreed with him and offered their own complaints:

“I liked this page months ago but this is the first time I have ever seen it in my news feed,” wrote one person.

“I reposted this on my wall.. The irony is that only a small part of my friends list actually sees it..” wrote another.

You can watch Muller’s full video below:

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