The Sept 2005 issue of Computers in Libraries has a solid article on screencasting, though it's called "demonstration authoring software" in the article. Written by two non-librarian IT folk, it starts with a nice introduction to the concept of screencasting, provides some solid tips for those who are new to the game, and includes a really nice chart comparing the features of the Big 3 - Camtasia Studio, Macromedia Captivate, and Qarbon Viewletbuilder Pro. The only drawback to the chart is that it shows the capabilities of Camtasia Studio 2.1, and 3.0 was recently released with enhancements that make the chart somewhat obsolete already. Ahh technology. The chart is what made the article for me - nice to have the side-by-side comparison like that.
The authors drop the following URL as a place where you can see what they've done, but there's only one presentation there right now: http://ucblibraries.colorado.edu/systems/samples.htm
I did some poking around on their site and found several more here, if you just want to see more.
If you've got a subscription to Academic Search Premier and are on campus you should be able to click right in to the article.
How We Used DEMONSTRATION AUTHORING SOFTWARE to Create Tutorials.
Computers in Libraries; Sep2005, Vol. 25 Issue 8, p6-64, 6p
You'll eventually be able to find the article in Expanded Academic ASAP and ABI Inform Trade & Industry, but this most recent issue hasn't been loaded in either of those products just yet...