The Art Of The Algorithms by Flame Film. English subs in spots.
One of the best explanations of the demoscene for outsiders I've ever seen. The pacing is spot on! You could show someone the first 5-10 minutes or so, and give them an excellent impression of the demo party atmosphere and the motivations of the people in it, without overwhelming them with the secondary details (realtime, sizecoding, oldskool platforms). Or they can watch the whole thing and learn those things in full detail, without it ever becoming dry. Must watch for 80s/90s nerds and warez junkies!
All credit for this video goes to the creator Moleman, just realized it was already uploaded here: https://www.youtube.com/watch?v=iRkZcTg1JWU