a great way to introduce your un-enlightened friends to the demo scene is with trixter's mindcandy dvd. just make sure they understand the context or they'll be all like "uhh i don't get it.' this is especially true with the old school side of the dvd.
the selection of demos in mindcandy is pretty good, but a demo i really want on dvd is tribes. when i saw it for the first time it burrowed deep into my brain and created a home for itself there. i don't think i've seen anything else as magical or brilliant. i actually never got to see the ending until many years later because it always crashed on my old pc. fortunately an emulator was made so you can watch it in windows (you need to do this now if you've never seen it before!). i think it's too late to get it onto the second demo dvd, but here's hoping for volume three. :)