If you are using Windows 64-bit, here's how to install the lossless codec for CamStudio:
http://www.haggardhosting.com/screen-recording/how-to-install-camstudio-...
This saved me a lot of headache trying to get the codec to show up in the video options.
It should be noted that this is non-portable and requires admin rights to accomplish. Additionally, the videos produced by the lossless codec will be unplayable on machines without the lossless codec installed.
Sometimes, the impossible can become possible, if you're awesome!