This is a fantastic tool.
screentoaster.com

You sign up, the browser loads a java applet, and before you know it you can record in full screen or in a rectangular section. Perfect for showing friends, coworkers, and grandma how set up her gmail account.

the best part about it is that it's entirely web-based and incredibly user friendly. you click a button or alt-s to start and pause recording, then after clicking "stop recording" you have the option to upload to youtube, upload straight to screentoaster (which gets through my work's internet filter as opposed to youtube), or create a .mov file.

have fun with it. i bookmarked it immediately.