Flytube

Flytube is an app to convert almost the entire Youtube catalogue into your own music library. With it you can open any YouTube video in a little floating window that can be moved anywhere on your screen. You can even put it in the background while you do other things.

Due to YouTube's terms of use, no app is allowed to continue playing videos while the screen is off – so to keep the videos from stopping, the screen won't turn off while you're using Flytube. Instead the video keeps playing in its own window on the lock screen.

In the setup options you can choose to fit the floating window to the edges of the screen or manually modify its size. Either way you can maximize the floating window with just a click.

Flytube is an excellent app for listening to music that lets you enjoy millions of YouTube songs in a simple, convenient way. You can also simply play a video in the background while you do something else.