Facebook’s battle for television ad dollars is about to begin in earnest. The company said today that Watch, its redesigned video platform, will begin rolling out to a small percentage of users tomorrow. Watch features original programming financed by Facebook, alongside videos from other creators, in a tab that will become personalized to your interests over time. It will begin replacing the current video tab for users tomorrow in Facebook’s apps for Android, iOS, the web, and television.

Shows available at launch include Nas Daily, featuring a creator who makes a daily video with his fans; Gabby Bernstein, an interactive show from the motivational speaker; and Kitchen Little, from publisher Tastemade, which follows kids making recipes with professional chefs. Facebook also reached a deal with Major League Baseball to broadcast one live game per week.

If successful, Facebook’s push into video programming could represent a major new source of revenue for the company, which has begun running out of room to place new ads in in the News Feed. It could also pose a strategic threat to other big video purveyors, including YouTube, Amazon, and Netflix. First, though, Facebook needs to prove that its users will watch longer video — and accompanying mid-roll advertisements — inside its apps.

It could represent a major new source of revenue for the company

Facebook paid creators to make some of the shows that will appear in the Watch tab, describing it as an effort to seed the app with original content for the launch. (It declined to name the programs.) Over time, the company plans to stop funding original shows with up-front payments, instead earning money by taking 45 percent of the revenues generated by ads.

The Watch tab arrives a little over a year after Facebook introduced a dedicated video tab into its main app. Until now, the tab has served up a seeming mishmash of videos from big publishers and pages that you follow. The Watch tab puts a lot of structure around videos, breaking them up into categories including “What friends are watching,” “most talked about,” and “what’s making people laugh.” (There’s also category for videos longer than 10 minutes.) The tab is divided into two sections: discover, which suggests videos for you to watch now, and the watchlist, which collects videos for you to watch later. If you find a video you like, you can follow the show, and new episodes will then appear inside the watchlist.

“What makes watching Facebook videos special is your friends.”

In interviews, Facebook played up the social aspect of its video platform, saying the Watch tab enabled communal viewing in a way that other services didn’t. “What makes watching Facebook videos special is your friends,” said Daniel Danker, who leads product management for video. “You discover videos through your friends. You often find yourself discussing videos with friends. Video has this amazing power to bring people together and build community.” Every show has a comment section, and some are associated with Facebook groups where fans can discuss new episodes in detail.

For now, publishers have to be invited onto the Watch tab. Over time, though, Facebook expects to let anyone publish to it. Right now there are “dozens” of shows available; by the time Watch is available globally, that number will be in the hundreds, Danker said.

Will it succeed? Facebook has plenty of advantages at launch. It has 2 billion people with their eyes glued to its app, and lately those people have demonstrated a healthy appetite for consuming video. It has commitments from big publishers and entertainment companies, who are desperate to find large new audiences and sustainable new sources of revenue. It has a product team that excels at copying the best bits of other services and integrating them into its own apps, iterating on them over time to maximize their addictiveness.

The marketplace for online video is insanely crowded

But it has disadvantages, too. For starters, the marketplace for online video is insanely crowded. At the high end, Netflix, Hulu, HBO, and Amazon dominate. In the realm of user-generated content, YouTube has a 12-year head start in attracting creators and viewers, who are watching an hour of video a day there. And Facebook’s first big push into video, which centered around live broadcasts, largely sputtered.

For now, though, it would seem unwise to underestimate Facebook. The company is rich, and can afford to be patient. It may not deliver a brilliant video tab in the short term. But given the billions of dollars at stake, I expect the company to keep trying until it does.