ScreenToaster, fresh out of restricted beta, is a web-based screencasting tool that can record your desktop from any computer with a browser and Java. It's great for quick demonstrations, and for beginners.
After signing up for a free account (name, password, email), you're pretty much set to go. Screentoaster supports Firefox, Internet Explorer, Google Chrome, Safari—actually, pretty much any browser that can run a Java applet. Get your desktop or apps set up, hit the "Start Recording" button on ScreenToaster's main page, and you'll end up with something like this:
Well, yours will be more exciting, since there would (hopefully) be a point to it other than demonstrating ScreenToaster. As noted in the video, the big downside is the inability to flip between rectangular-area-mode and full-screen shots, or zoom on the desktop with the app itself. Similar in many ways to Screencast-O-Matic, but I find ScreenToaster's videos to be smoother, and the presentation a lot nicer. There's also some nice features to pull from once you're done recording:
Looks like direct YouTube uploading and SWF downloading are coming down the pike, but it'd be nice to get better embedding options, a la Screencast-O-Matic, and QuickTime-format downloads. Still, for quick-hit screencasts or those who don't like to bog down with software, ScreenToaster is a nice option. It's free, requires a Java runtime package to run.