I don't know a lot about screen capture but I've been using CamStudio lately for a project, and I can vouch for its goodness (for simple work at least) and freeness. I just tried it on a Dominions 3 battle and it worked acceptably well.
Here's how I record videos:
Capture the basic video into a giant, weakly compressed file with CamStudio, which has been configured to use the lossless CamStudio codec. (I think you have to download this codec separately.)
Use SUPER (
http://www.erightsoft.com/SUPER.html, also free) to convert that into a much smaller, better-compressed file that uses some awesome lossy format like H.264. (There are probably a lot of free conversion tools; SUPER is the first acceptably good one I was able to find.)