Some days ago , the Slicium #retrocomputing association were showcasing #oscilloscope #demoscene productions. The trick is incredible : it's just a stereo music playing, the video is encoded in some frequency, and left and right encode X and Y.. sort of... if i get it.
....
Oh, there is a list of prods on pouet:
https://m.pouet.net/lists.php?which=194
... else it's called #oscilloscopemusic and there is a lot about it.