Share a YouTube video with this application or use the clipboard, the application then get the stream and open it with local application, VLC is a compatible local application. The video is then handle by the local application which can allow to put in background (VLC does allow it).
This app has features you may not like.
Although APK downloads are available below to give you the choice, you should be aware that by installing that way you will not receive update notifications and it's a less secure way to download. We recommend that you install the F-Droid client and use that.Download F-Droid