How do you create animated presentation in screencast
I've used ScreenFlow to do this a number of times.  It's very simple to use and worth the $100.  You can buy it off the website or from the Mac App Store.

Also, until 13 May 2011, you can buy it as part of the MacLegion bundle, which means you'd get it (plus a number of applications) for $50.  However, that will be a non-MacAppStore license: http://maclegion.com/