Pixel Prospector has a great how-to on recording and editing your own in-game videos, not only in D3D/OpenGl but in browser and windowed games as well. The surprise here is that it's not just a "You need to buy fraps and a $900 video editing package" advertisement, but a freeware alternative solution as well.
Two programs specified are worth mentioning on their own here. First is Taksi, a freeware in-game video recording app that has finally been updated to include audio, the tutorial still suggests installing the Fraps demo and using the installed codec for recording though. Secondly is iWisoft Free Video Converter, a simple cut and trim video editor with a full bevy of pre-configured output formats. This editor has an unfortunate homepage popup on closing, but no other nags or spyware.