That one blew me away. Another one I remember fondly is Dope by Complex[1], from 1995.
My computer at the time could barely play the the soundtrack itself in the tracker, it had so many active channels. The demo itself was a slideshow. Fortunately my friend had a 486/DX4 100MHz, so I got to watch it there.
To put this in perspective, there's no graphical acceleration involved here at all, everything pixel to be done on the CPU. And the microcontroller in the coffee maker at work is about as fast[2] as my friends 486[3].