1. Buffer: Play this video before starting the music player (not necessary in Firefox)
2. Play: Click on a song to play, if it throws a "video unavailable" error just click again. Songs are on loop by default. "play all" plays a whole list in order, the playlist is on loop. "play none" stops the music.
3. Further control: click to toggle player position. (this is a fallback to start the player manually in case the buffer doesn't work.)