This is a collection of videos from Halo:CE on the Xbox from around 2003. Most of it is with modding or other hacks (everything but the first clip!). The source material was captured with various weird USB or PCI devices, so sound and image quality varies greatly. Sound can be especially bad, beware.
Blog post: http://andreasaronsson.com/2008/04/11/halo-video-compilation/