I've been looking for that video for some time, i saw it ages ago and couldn't remember what it was.
Thought it might have been a dream i had because nothing could possibly be that cool
musicthing.blogspot.com recently featured some kind of open sourced version of these things, apparently you just need a camera, a projector and some software. And a big transparent table, I guess.
The best part is that the software that recognizes the objects on the table is free. If you look for the reactable website it's on there. It can even transmit midi messages, so you could control your sk-1 with highly liquid kit from it.