Doom 3 Movies
Giant Ass E3 2003 Video
A 160 meg monster of a movie, showing the E3 2K3 preview video at 640x480.
E3 2003 Video
The Doom 3 vid that was shown of at the Electronic Entertainment Expo in May 2003. Shows more gameplay footage, as well as first looks at new monsters like the bee baby and the upside down spider head thingy.
ATI Doom 3 Video
ATI has released a video showing off their new Radeon 9700 card which, among other things, has a little segment with John Carmack and shows off some Doom 3 footage. As far as I know all the footage has been seen before (although I don't really remember the first scene) but it's quite high-quality so you might want to check it out. 77 megs.
Doom III: The Legacy Movie
No, not the source port. The official version of a seven-minute movie being shown to the crowds at E3 has hit the internet. This movie mixes interviews with various idders, with footage from Doom and Doom 2, and yes, new video clips of Doom 3.
Footage from the Macworld conference in February 2001. This video was the first media ever released of the Doom 3 engine technology and shows various locales and monsters.
Bootlegged E3 Footage
It exists, but id Software didn't look kindly on its being covertly recorded and disseminated, so you will not find it here.