It appears to be producing an AC voltage of 2.8V but at miniscule current output.
It's probably on a magnetic bearing when the friction would be so little so to allow it to spin for ages. The spinning disc has rotational kinetic energy, imparted by the finger that set it on its way in the first place - those magnets on the underside of spinning disc have large mass relative to the size and scale of the closed dynamic system'.
Being virtually frictionless, the only power being taken out of the system is 2.8V at say 50 microAmps.
It could go on for ages like that until it stops.
Come back tomorrow and see if it is still spinning.