I talked to Anali Perry, who is in these videos and she told me they have a team that works on these. The actual recording takes anywhere from 30-60 minutes, she improvises a good amount and they try hard to inject humor into it, so multiple takes. They use a student intern for some of the video editing.
Photo by Mr.KIO via Flickr Creative Commons: http://www.flickr.com/photos/igievil/4401962584/
Informal screencasts + YouTube = no or low cost in time and money. I use Captivate.
These are low barrier to our users and low barrier to us (no programming, little time needed to set up).