It might be promoted to the Beta already as well.
Facebook adds new Video tab to the navigation bar right between "friend requests" and "profile" tabs. After opening Facebook app for the first time, this tab will be highlighted.
It seems like there still some experiments running on for that tab as well. In the Videos tab itself, you might see the Watchlist section with important videos from accounts you follow. It will disappear if all videos were viewed.
Below the watchlist, you might see "Top videos for you" with a bunch of videos coming from liked pages which you don't follow or from facebook recommendations.
I am not quite sure if I am happy with this "Top videos for you" list. Sometimes it becomes tricky to mark all recommended videos as "I don't want to see this anymore". Keeping in mind recent activities with IGTV and sync between Facebook and Instagram stories I would say that this "Videos" tab might be a preparation to the IGTV to Facebook integration.
Thanks to beta_previewer for pointing it out!