How can I like a YouTube video while it's in full screen mode?
I can't see any buttons to do so, and this unofficial guide to keyboard shortcuts doesn't mention liking a video.
You actually can like a video while in fullscreen. At least I am able to. Found it by accident after having given up long ago. While in fullscreen, scroll up on the window (I'm using a Macbook pro with Chrome & using two-finger scroll on touch pad), this will bring up the usual YouTube buttons, comments and side vids! You can like the video and scroll back up to continue watching in fullscreen.
YouTube removed that feature long back. You can only like the video by leaving the fullscreen now
After watching video you can press ESC and click on thumsup below video.