Wow, I'm totally excited about the Jing project. Jing is a free little application for Macintosh and Windows computers that makes it easy for anyone to capture the action on their screen and share it with others. Registration is free with a valid email address, and they even provide you with free hosting of your screen captures (pictures or movies) on the screencast.com website. I've used several shareware and commercial apps in the past to make screen recordings, but this is by far the easiest, cheapest, and most elegant solution I've ever used--and it works the same on Mac and Win computers!
Here's a little movie I made to illustrate how to view file name extensions in Windows XP.