I can't seem to see the video here at work... probably don't have the right codec (and I'm too lazy to figure it out).. but I do think they're pretty cool sounding.
Hmmm... I've got a bunch of old HDD's here... maybe I'll build a set for my desk.
pretty much if youve got enough power running thru the speaker wires, you can make alot of things create audible waves. its really not at all complicated. http://www.plasmatweeter.de/