This is one of those things like "What wine is the best?" or "Do these jeans make me look fat?" - but here goes...
The tools noted above and on the "round up" are solid, although I have found Captivate to be too much for the typical user to master IF all that is wanted is to bang out a quick tutorial.
Perhaps the key questions are these - and I admit the answers will vary wildly based on what you are trying to accomplish...
- SOUND - is a voiceover (VO) actually necessary? In other words, are spoken words critical to communicating the content and ideas? If so, then you are talking about the tools already noted on this thread. Be aware however that getting the sound 'right' takes practice. Why? Using sound requires more upfront and post-production work.
Upfront work involves preparing a tight script, practicing to remove the "uhs" from your delivery, and knowing/investing enough to get a decent mic (not the crappy one in your laptop, please!). Bad sound is the #1 reason people click away from a podcast or video. (Slow pacing being #1b...)
Post-production work involve editing; getting the pacing right or combining two different tracks for the right cadence.
- ACTION - is live action really the best way. I know we all want to free our inner JJ Abrams, but sometimes the viewer can be distracted and confused by too much motion and detail. As an example, check out InPics which does a great job educating people on Open Office using static screen shots.
Again, live action means using a dedicated tool.
NOW, if sound and action are not essential, explore using Google's free Picasa which does a great job producing a 'slide show' type presentation of a sort of kiosk nature. Powerpoint does the same, but hey, let's try to use the free stuff, right?
A picture can be worth 1k words to be sure, but that doesn't necessary mean a Moving Picture is worth any more.
PS. Contact me offline for more on this topic as this is a LOB (line of business) for me but this answer is not offered as a solicitation...