The demoscene was also not so much into "open source".
Code was often kept secret, to add to the mysticism of the amazing algorithms (which often turned out to be very clever tricks, and not academic breakthroughs), or to simply hide the fact that the code was a terrible mess.
With regards to Linux -- Avoozl and I wrote a 4k intro for it in 1999 [1]. It was quite a lot of effort, with custom ELF headers to shave off a few bytes. There were but few people willing to run the thing as root though. (This was a requirement for svgalib, and us demosceners couldn't understand why unix sysadmins took offence with that :)