This one took me a while but I finally found a software stack that works well for screen casts in Ubuntu 10.10 and YouTube. recordmydesktop is great for capturing the full screen, a single screen, or a small portion of your display. The other product is Winff for converting the ogv file to an avi. This was actually the most painful part of the process as many products came and went but still exist in the wild world of the Internet. The stack works really well. Just record, convert, and upload the YouTube.
Both are available from the Ubuntu repository via the Package Manager.
Below is a screen cast of me actually type this blog. It records audio from any microphone you have configure and thus you'll here me typing in the first part of the video.
And here's a screen cast of using WinFF to convert OGV to an AVI file. You can view this file below.
Good luck and may the Force be with you.