[JKCalhoun]

I recall a display at the Museum of Science and Industry back in the early 1970's that featured steel balls bouncing on steel plinths not unlike the video.

I recall too a pair of angled plinths and the steel balls would appear from an opening in the display, drop and bounce from one plinth to the other before exiting (repeat).

No amount of googling has helped shed any light as to "What that was". Perhaps this metallic glass.

(Also recall a computer that you could play Tic-Tac-Toe against. The input was a more or less a telephone keypad, the display large neon X's and O's. Seven year old me, or thereabouts, was fascinated to read that the computer had never yet lost.)

[geon]

In the 70s only thin foil or wires could be produced. The alloy in the video was invented in 1992.

https://en.m.wikipedia.org/wiki/Amorphous_metal

[Vecr]

Possibly computer controlled bumpers? Making the movement imperceptible would have been hard, but I think possible. Or air jets/magnets, you could do those.