I kinda figured it was faked, for the exact reason you just said. Though, in fairness, he could just have the keyboard set up for a single octave that repeats, that way he can hit the same note on different keys so the balls don't hit each other trying for those short notes. It's kind of cheating, but then again, he's not exactly using a real piano in the first place. THAT I would like to see... juggle marbles or ball bearings of a regular piano. :-)