Facebook is introducing video advertising within its mobile apps, but for now the new units will be restricted to ads for other apps, rather than made available for a wider selection of brands.
The new video feature is part of Facebook's Mobile App Ads for Installs scheme, which developers use to drive people to their apps on Apple's App Store or Android's Google Play store from within Facebook.
They've become an increasingly common site in Facebook users' mobile news feeds in recent months, particularly for free-to-play games, with developers keen to use Facebook as an alternative discovery channel to Apple and Google's app stores.
Now those units will come with videos of the apps. "Potential customers will be able to click play to watch a video featuring your mobile app before installing the app," explained Facebook in a post on its Developers blog.
"Video creative has proven to be an effective way to drive engagement in News Feed, and we look forward to helping developers use their video creative to find new app installs."
Facebook cites slot-machine game DoubleDown Slots & Poker as one of the first examples of a game taking advantage, quoting its vice president of interactive marketing as claiming "increased install rates and decreased costs per install" in its early tests of the new feature.
The videos do not automatically start playing when encountered in a user's mobile news feed, so are unlikely to spark a backlash over their intrusiveness. In September, Facebook tested a feature to automatically play videos from other users when they appeared in its apps, which was seen as a precursor for this feature being used for video advertisements too.
Facebook is also adding a new way for app developers to pay for the ads they buy on its service. Until now, they've paid on a cost-per-click (CPC) or optimised cost per impression (oCPM) basis, but now they can opt for cost per action (CPA) instead, only paying when people download and install their app from an ad.
"Based on internal Facebook tests, buying on CPA drives, on average, 20% lower cost per install than buying on CPC," claims Facebook's blog post.