Chrome added an experimental new picture in picture feature for videos. You get a re-sizable video window that sits on top your other windows. So far it only works with Youtube. Doesn't seem to work with Twitch or the premium player so it doesn't work with GB Infinite or premium videos. Still pretty great.
Once you have it installed you need to type chrome://flags into your address bar and then go to
and change the setting from default to enabled.