Rick said "Actually, what I see likely being used most to create the screencasting is Adobe Presenter Video Creator."
The problem for some (including me) is that there is no Mac version available. The Mac version of Camtasia is very respectable nowadays. I like the simplicity of Presenter...just not sure why when Adobe has Mac version of almost all their software, they haven't put together a version for Presenter. I had heard it's a Powerpoint issue but you can use presenter outside of Powerpoint...not everyone generates their training from Powerpoint.
Dave