is playing the nostalgia card in its latest bid to drive up video viewing and video ad sales: using TV reruns.

The social-media giant is launching every episode of Joss Whedon’s supernatural drama “Buffy the Vampire Slayer” and spinoff “Angel” along with sci-fi show “Firefly” on Facebook Watch for free to users the U.S. All 268 episodes of the shows will be available to watch starting Friday, Nov. 30, under a licensing pact with 20th Century Fox Television.

Facebook has set up dedicated show pages for each of the series: “Buffy the Vampire Slayer” will be available at this link; “Angel” is available at this link; and “Firefly” is streaming here.

The trio of shows, which aired on TV more than 15 years ago, is not exclusive to Facebook: All seasons of the three also are available on Hulu’s subscription service.

But Facebook believes the cult-favorite shows — particularly “Buffy” — will drive up watch time by letting fans experience the series in a brand-new, social way (along with the fact they’re free to watch). This week it expanded the Watch Party co-viewing feature to everyone on Facebook, making it possible for users to start Watch Parties from their Timeline or from any public video on Facebook. The company’s hope is that “Buffy,” “Angel” and “Firefly” will spawn thousands of Watch Party sessions.

“What we’ve been focused on Watch is building a people-centric video platform, creating a social viewing experience where you can connect with other people who love the shows, and even the creatives who worked on them,” said Matthew Henick, Facebook’s head of content planning and strategy for media partnerships.

The three shows from Joss Whedon in particular “have incredibly dedicated fanbases that have persisted and even grown online,” Henick said, noting that a TV reboot of “Buffy the Vampire Slayer” is in development at 20th Century Fox Television. “This is great content to experiment with.”

Facebook also is enlisting talent from the shows to promote the free streaming — including Sarah Michelle Gellar, star of the “Buffy the Vampire Slayer” series. On Friday, Gellar announced the free streaming of the show in a video on her Facebook Page, which has nearly 1 million followers, in which she underscored the platform’s co-viewing features to watch along with other “Buffy” fans on Facebook.

“It’s time to slay all day,” Gellar says in the announcement.

Other talent from “Buffy,” “Angel” and “Firefly” are expected to participate in live conversations via Watch Party, according to Facebook. Facebook has scheduled Watch Parties for each show: The “Buffy” co-viewing will kick off at 3 p.m. PT on Friday (Nov. 30); “Angel” will start on Dec. 1 at 12 p.m. PT; and “Firefly” will launch Dec. 2 at 12 p.m. PT.

Asked whether Facebook is seeking other TV show to bring the platform, Henick said, “I wouldn’t say we have a huge licensing plan… We have a balanced portfolio.”

First launched in the U.S. in August 2017, Facebook Watch includes original series and other content, live sports, and programming produced by independent creators. The deal with 20th Century Fox TV is “part of our larger strategy,” Henick said. “We have lots of different ways to get content onto the platform, and we’ll find a variety of ways to do that.”

Facebook is streaming all seven seasons of “Buffy the Vampire Slayer” (144 episodes), five seasons of “Angel” (110 episodes) and the single season of “Firefly” (14 episodes). The company declined to disclose how long the shows will be available on Facebook or discuss other terms. The episodes of the shows will include Facebook’s midroll ad breaks, with ads sold by Facebook.

Facebook has been trying to steer users to Watch, where it can monetize video ads more effectively compared with videos in users’ News Feeds. But according to a survey conducted this spring, half of U.S. adult Facebook users had never even heard of Facebook Watch.

“Video is a critical part of the future. It will end up being a large part of our business as well,” CEO Mark Zuckerberg told analysts on the company’s Q3 earnings call last month. He also admitted, “We are well behind YouTube.”

Initially, “Buffy the Vampire Slayer,” “Angel” and “Firefly” will be available on mobile and web platforms, with plans to later make them available on Facebook’s connected-TV apps.

“We want to make sure we’re presenting the best social experience to start, and where people interacting are on mobile and web,” Henick said. “What we’re looking for are meaningful connections between fans.”