A New Hope
One of the most-famous internet videos was of an unfortunate boy acting out a light-sabre duel with an invisble opponent. Known as 'The Star Wars Kid', he showed a unique enthusiasm and passion as he wielded his 'light-sabre', and fascinated web-users around the world.
Here's the latest edited version of the Star Wars Kid - A New Hope:

http://video.google.com/videoplay?docid=-2894093448203053618&q=new+star+wars+kid
This time I'll remember to credit both Sam and Adam, who passed on to me 'A New Hope'.
World's Longest Startup sound
If you've ever been amused by the reactions when someone starts up their laptop, you'll love this video...

http://www.prangstgrup.com/startupsound/quicktime.php
Thanks to my brother-in-law, Mark, who passed this on to me.
Trampoline Scootering!
How much fun is this?! You've seen trampolining. And you've watched a scooter fly past. You may even have had a go. But I bet you've never seen
Trampoline Scootering!
http://video.google.com/videoplay?docid=746257003026829792&q=scootering
BMW car ad
This amusing short film kick-started a whole genre of internet movies. Clive Owen stars as the driver for a star, Madonna, in a getaway from her bodyguards. Directed by Guy Ritchie.
http://video.google.com/videoplay?docid=5836917188695547582&q=bmw+madonna