Facebook has resisted the practice of pre-roll ads. Now, according to knowledgeable advertisers, in a major shift the company says it plans to test such ads for Watch shows. The ban on pre-roll ads came directly from chief executive Mark Zuckerberg who stressed that users came to the site to look at a feed, not watch one specific piece of content. This year, however, Facebook debuted Watch, where TV studios, publishers and celebrities can try to sell advertising against their shows, an ideal format for pre-roll ads.

AdAge reports that, “the move was part of a broader war among digital platforms and publishers to win at video, where marketers will pay more than for other kinds of ads.”

“YouTube already established that people will sit through and tolerate pre-roll,” said WhoSay chief executive Steve Ellis. “It’s proven that they haven’t sent consumers fleeing, so it makes sense that Facebook would pursue a similar strategy as it builds out its original content experience.”

In the past, Facebook videos tended to be “shorter clips that depend on impulse viewers.” In contrast, “Watch was designed to draw audiences of loyal, returning viewers in a setting more like TV.”

In that context, pre-roll ads are a “guarantee of ads being seen at the outset of a video.” “A downside of Facebook News Feed inventory is that it can be easily scrolled past by users, whereas pre-roll or mid-roll in Watch guarantees eyeballs against our clients’ content,” said Huge director of paid social Mark Sytsma. “The ability to purchase a known or guaranteed amount of inventory has always been a gap when buying on Facebook. This ad product would fill that hole.”

Watch debuted with mid-roll ads, but “some publishers and advertisers say those ads haven’t been optimal.” “There have been comments from viewers about how annoying the ads are,” said one publishing executive. “They say they would rather watch pre-roll than watch a video and be interrupted.”

Facebook reports that mid-roll ads have a 70 percent completion rate, but has not, however, “revealed data specific to ad completion in Watch.” Facebook is currently “updating Watch’s programming” with renewals of some existing shows. New shows under development include those from Business Insider, Hearst, Tastemade, Refinery29 and Group Nine. The goal is to attract and retain repeat viewers who are “most likely to tolerate pre-roll commercials.”