Watch demos all day [video]
tv.pouet.net
tv.pouet.net
I'll watch later.
<nostalgia>
I remember when I was downloading the Hornet archive (now at https://hornet.org/) or demos from The Scene (http://scene.org) using the university connection back in the 56K modem days.
I still remember my first time, Second Reality by Future Crew :-)
Unfortunately due to lack of time my last contact with the demoscene was with Iconoclast by Andromeda Software Development (http://www.asd.gr)
</nostalgia>
I access it for a couple years via a gopher client installed on the 20-minute free dial-up internet account I tricked my local school district into giving to me.
hornet.eng.ufl.edu
Another modern kinda "demo scene" is http://www.shadertoy.com - and a lot of the same people :). Enjoy :D
https://www.youtube.com/watch?v=iRkZcTg1JWU
*Granted, it's 5 years old, but still awesome :D!
Made a number of screens in that group around 1990 :-)
It's virtually unknown due to it being almost impossible to monetize in the way traditional art movements have been (where a single instance is made by an artist and you can purchase and own that one "true" instance, all other versions are just copies). It doesn't seem to have strong political or philosophical aims like many art movements do. Most "demos" are produced by small teams operating almost entirely under pseudonyms so single authorship and artist identification is also very hard to pin down.
The art is usually highly abstract, or plays with familiar forms in abstract ways. If there's a statement to be made it's usually in terms of create productions that push what we think computing can do, and to do it in a way that's not of any particular use to purely commercial or utilitarian interests.
Demoscene music has a variety of identifiable subgenres, often based in non-scene genres, but with several identifiable themes that don't generally exist in non-demoscene music.
It has some loose "rules" for what is and isn't a demoscene production, but it's kind of like pornography, you know it when you see it (or hear it). There are literally hundreds of thousands of productions.