Here's a screencast of one my favorite apps for the iPad: iCabMobile. This app allows users to download media, from virtually any website, directly to the iPad that can then be used in other programs (Keynote, etc).
For this screencast, I used a program called "Reflection" which allows the iPad to wirelessly project to a desktop (in this case, a Mac) computer. It has a built in recording feature that automatically records the screen of the iPad. I had to bring this video into another program to do the voiceover. Ironically, as I was completing this project, I had some friends on Twitter share that Display Recorder is now available that will record the screen AND the audio, thus allowing for a seamless screencast. Reflection is a $9.99 app, and the Display Recorder app is also $9.99.