Comment by theandrewbailey

The difference between procedural generation and a video is similar to the difference between raster and vector graphics. Demoscene intros like this are more like your computer giving a live performance from scratch than playing a movie. Ideas like video compression don't really apply. They create 3D models and textures from simple math functions and filters, make a world from them, add more math functions for camera movements, and play some synthesized music that's more akin to MIDI than MP3 (to put it simply).