The next time you log into your Facebook account, there’s a good chance you could run into a video ad that will begin playing automatically.

Facebook announced it will begin rolling out video ads in users’ news feeds starting with a clip for “Divergent,” an upcoming film.

The videos will appear on Facebook’s website and mobile apps. As users scroll down their News Feed, the ads will start to play on their own. No audio will be heard unless users click or tap the video or put it in full-screen mode.

On mobile, Facebook assures users that the ads won’t waste their limited data plans. The company said the ads will only download while users are connected to a Wi-Fi network.

At times, the ads will preload while users are connected to a Wi-Fi network and play later, even if a user is no longer connected to Wi-Fi. This could mean that the already large Facebook app will now take up even more storage space on users’ phones.

Facebook has been toying with the idea of video ads for some time now. It had signaled the move when it began playing videos without first requiring users to prompt the clips to play.

For now, Facebook says this is just a test that only a small number of people will see. As for opting out, Facebook said users who don’t want to see the new ads should simply keep scrolling on their feeds.