As you can see, different positions correlate to different types of sounds and tempos. There's no explanation provided for how the machine works, but that's completely unnecessary. It's a nonsense machine, after all.
It doesn't make 'music' when you 'move your arms'. May I suggest not to spend all your time playing Wii Music? ;)
Both electro excited Mokugyo are operated by a corresponding switch in each hand. And each produce a 'note', and any combination of notes by the player results in music. Maybe it is something you can't relate to (as it isn't a banjo) but I wouldn't classify it as nonsense, but it does look pretty silly.