When you say physics-based I'm not sure if you mean that this is a physics engine being played out, or something that was still animated manually. Well, I really like this. The music is perfect and the graphics are simple but elegant. At times it seems a little too linear, though. The ball makes up too large of a percentage of the animation, and at times it lacks realism. This appeared mainly with the dominoes, which fell perfectly in line, and the ball, which followed the track perfectly even during loops - it might have been better to have it come away from the track, only to fall back on at the other end and continue rolling.
That being said I like the different angles and slow motion that a filmed Rube Goldberg machine would not be able to deliver. Very interesting, seems like it would make a really good demo.