YouTube now a days are experimenting with filling more stuff into the full-screen video interface on Android platform. We can see the comments section as well as video description in the full screen mode which was previously a distraction-free mode. And now YouTube is planning to do almost everything in the full-screen that was previously limited to vertical interface.
The new full-screen interface will add some new buttons which you usually find below the video in the vertical mode. These buttons include a like, dislike, comments and share button. It also include an option to add the video to a playlist. When you will tap the title at the top you can also access the video description. In the new full-screen mode you can now no longer swipe up in order to view the suggested videos. Now there is a button in the bottom right corner that will provide you to access these.