How to Create Video Clips of Video Games?

I need to create video clips of specific parts of video games to show online.

This would include web-based games, PC-based games, and console games.

Any suggestions how I go about this?

(I am aware of the legal constraints that may pertain; those matters will be addressed by a legal professional.)

Thanks for any light you can shed.

record your console through a dvd/hardrive recorder.
capture screen images using camtasia studio.