I think it currently only works with videos in Safari/stock apps. Not sure if that's coming in a later beta or whether YouTube etc. need to be updated, I'd assume the latter.
All apps that use the standard video view controller can do PiP. Apps that use custom displays like YouTube need to be updated in order to make use of it.
YES! I have been doing it since I got the beta and I absolutely love it. I just embed my videos into a website. Mine is 9youtubelinks.weebly.com . I highly recommend weekly. It took me no longer than two minutes to get it up and running .But can you work around by viewing YouTube in safari? But Apple is going to allow third party apps to use the Pip feature right? Right??
They should be able to support it, Apple showed it off with the Watch ESPN app which doesn't support background audio and doesn't even use the default iOS video player.There shouldn't really be any reason for Youtube not to support it unless Apple mandates that PiP requires them to also support background audio.Youtubes worry on backgrounding was using for audio only, yes? PiP is not audio only, video still on screen. Can't see any reason why wouldn't do so.