[DonRotolo]

Adobe Captivate is a great program; it is not free but they offer a free trial. Excellent for screen captures with animation, mouse movement and clicks. Not so good with actual video.

Before picking a tool (any tool), first write your script: what exactly will each screen show, what images and text will appear on screen, and what voice-over will be there. That will help you figure out which tool might be best, and it will minimize the time spent actually creating it. My 2 cents'