Facebook may be a latecomer to the streaming video market, but the company thinks it can generate money by making it more social.

"Video has always been social, even before the internet, when everybody was watching the same few channels," said Fidji Simo, Facebook's head of video, in an interview. "Everyone was talking about their favorite shows around the water cooler."

For Facebook, the challenge is not to mimic Netflix or YouTube, which have built successful models on the backs of consumers who binge watch, but to get people to watch shows together again, even when they're viewing from their phones or other personal devices.

"We can do that because all of your friends are on Facebook," Simo said.

There's a ton of money at stake. While digital advertising is increasing, brands only spend about $13 billion a year on online video according to Andy Fisher, chief analytics officer at marketing agency Merkle. Meanwhile, $70 billion a year in the U.S. is still spent on TV ads, said eMarketer.

To get a bigger piece of the pie, Facebook is boosting its investment in Facebook Watch, a video service announced a year ago, which includes original shows and other TV-like content. Earlier this year, the company started talking to media buyers about allowing shorter ad-supported content, and in June talked to social media stars about broadening ad opportunities.

On Thursday, Facebook expanded Watch across the the world. Until now, it's only been available in the U.S., with shows, live sporting events and shorter clips from online creators and media companies. About 50 million people in the U.S. watched videos for at least one minute a month, according to Facebook.