It's a cool animation, but there is no way that could ever be live.
There are too many frictional forces such as air resistance acting on the balls for such a thing to be feasible, and all of the instruments are moving, so (with particular note to the strings and the moving xylophone blocks) the movement will affect the momentum of the ball and should change the direction of it. As Zmann said as well, the propulsion of such balls is also not really feasible, since they are supposedly made of steel and so the forces needed to propel them will definitely be succeptible to error, while even tiny errors in them or the instruments will cause direction deviations.
It's definitely an animation - balls don't defy the laws of physics, and neither do musical instruments.
Plus, the title screen does say "
Music driven computer animation"
.
[Edited by agaricus5 on 07-16-2004 at 07:10 PM GMT]
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Resident Medic/Mycologist