To date, the battle between YouTube and Facebook has centered on winning the hearts and minds of advertisers, online video publishers and creators. If the last few weeks are any indication, there’s another category of content creator YouTube should be concerned about losing some of its value to: TV networks.

On June 15, Amazon (along with Netflix and Hulu, a new breed of TV network) made the first episode of its comedy series Catastrophe available for free on Facebook. A week later, HBO did the same with two of its newest series, Ballers and The Brink.

On the surface, this might not seem like anything special. Online sampling of new programming is not new to TV networks, which are trying everything under the sun to reach audiences who are increasingly watching TV and other video content on digital platforms. What makes it interesting, though, is that YouTube used to be the only place on the Web that guaranteed the biggest video audience possible. Now, not so much.

Declining viewership drives marketing pivot.

“Right now, the world of video content distribution is right on the edge of total chaos,” said James Nail, a principal analyst at Forrester Research. Previously, if a network had a new show to promote, it would use a couple minutes of commercial time during the nightly broadcast. That’s not enough anymore.

And yet, it’s not as if people aren’t watching TV. Cord-cutting is a real phenomenon, according to Erik Brannon, a senior researcher and analyst for IHS Technology. They’re just not electing to pay for television in the traditional manner.

This is why HBO launched HBO Now and other networks like Showtime are following suit — to reach the 10 million broadband households in the U.S. that don’t pay for cable or satellite TV.

By allowing them to sample shows on social platforms, networks can also convince users in these households to pay for their new digital video services.

“Networks need to evolve at a pace that will find consumers as quickly as their behaviors change,” said Jim Marsh, VP of digital and social media for HBO. “Digital sampling is an effective way for us to introduce our programming to our current and potential subscribers. Ultimately we’re trying to create new fans.”

“It’s part of an overall strategy to include households that are excluded,” said Brannon. “Get people hooked and get people subscribing. I don’t think it’s going to result in a heck of a lot of pay-TV adoption. It’s a vehicle for OTT adoption.”