Google has just began rolling out version 5.0.21 of its YouTube app to Android devices (via Android Police). The update is arguably the biggest the app has ever seen and includes a brand new interface, as well as much more. The interface is now entirely based on cards, much like the Google+ app. The slide-out navigation has also been changed, though only slightly. Finally, you can now give videos a thumbs up or thumbs down, or flag it, without having to expand the video description.
Also new is in-app multi-tasking. Now, you can minimize any video to a tiny window in the corner and continue to let it play, even when navigating through other portions of the app. You can bring it back to the forefront by tapping or dragging the window back to the center and dismiss it by swiping away the card.
Samsung U28E590D 28-Inch 4K Monitor
Other new features include the ability to search for playlists, easier access to the HD and closed-caption toggles, a brand new app icon, an improved landscape interface on tablets, and undoubtedly much more.
The update is rolling out to devices in stages, so if you may have to wait awhile for yours to get it. Keep an eye on the Play Store for the latest, though.