Millions of people watch YouTube videos on their phones nowadays, but despite displays getting larger and larger, we all wish we had a bit more screen estate to enjoy the experience. Switching to fullscreen and landscape helps a lot, but you lose a bit of the YouTube experience. Some actions, like thumbs-up and down, or viewing the channel and subscribing aren't immediately accessible, so you have to get out of the fullscreen mode to do those. Not anymore though.
You may recall that two years ago, YouTube began rolling out content suggestion thumbnails that are accessible from a swipe up in the fullscreen landscape UI. No changes were made to that overlay until two months ago, when a new channel element was added. It lets you view the channel name, number of subscribers, subscribe or not, and enable notifications.
Now, another element is showing up, below the recommended videos. There's a new bar with four icons to quickly like, thumbs-down, share, or add the video to a playlist. The latter two are also accessible from the main fullscreen playback interface (when you just tap, or tap to pause), but the former aren't and it's very handy to have them here.
So it's now possible to open a video in fullscreen, like it, switch to another recommended one from a channel you don't know, subscribe and enable alerts, go to another video, add a thumbs-down if it's not your style, all without leaving the fullscreen interface at any point. I give a thumbs-up to that.
The change appears to be server-side, as I have this now on both YouTube v14.19.54 beta and 14.20.50 beta, though it wasn't live for me yesterday on either. You can grab the latest version from APK Mirror or simply join the official beta test on the Play Store.