My first thought was fake, because the sounds were too clean & full sounding (not sure of the technical term).
Would be easier to far easier to program the song on a computer than create the machine - so you could create a machine that kind of mimes to a song.
But then I watched till 2:48 when you can see the what I guess is a bunch of mikes or pickups through the machine, and the bass, feeding into a mixer onboard.
So it's actually mechanical/electrical...
Imagine the look on a parents face when Little Johnny comes home from school with his new musical instrument.
It's awesome and would have taken a heap of work to make it but it's actually far simpler than it looks
The big wheel has pins that open small gates that drop balls and they fall on the noise maker underneath. He's actually fretting the bass with his left hand.
The bulk of the machine is lots of fancy hoppers and carriers to lift the balls back up.
This is machine that actually plays the instruments.
