I find them great to relax to. Most of it is terrific chillout music and visuals.

The demoscene is an international computer art subculture focused on producing demos: self-contained, sometimes extremely small, computer programs that produce audiovisual presentations. The purpose of a demo is to show off programming, visual art, and musical skills. Demos and other demoscene productions (graphics, music, videos, games) are shared, voted on and released online at festivals known as demoparties.

https://en.wikipedia.org/wiki/Demoscene