iPad: iOS 9 introduced multitasking to the iPad way back in September of 2015 and today Google finally updated the YouTube app to support these new multitasking modes. YouTube now supports Slide Over and Split View modes for watching videos in the app, but for some reason, Picture-in-Picture isn't supported at all. As always, Split View is compatible with the iPad Air 2, the iPad Pro and the iPad Mini 4. Slide Over's compatible with the iPad Air and newer, the iPad Mini and newer and the iPad Pro.
YouTube (Free) [iTunes App Store]