I am using CamStudio to make some instructional videos about Visual Studio for our development team, and one of the videos needed some editing to remove audio and video mistakes and to add in a better ending. CamStudio outputs to .avi files, and they look pretty good, with the program source code being quite readable. However, after making the edits using WMM, it has rendered the results to a noticeable loss in quality. It has gone from from fairly sharp in focus and adequately readable to recognizable but somewhat blurred. It has also inflated the size of the new .avi file to three times its original size (before cropping half of the vido out!). And the .wmv I attempted to render was was certainly smaller but simply horrible-looking. The left image here is the original video, and the right image is WMM's rendering in .avi format:

I have to be doing something wrong, but I know nothing about how to use WMM (my first use of it). I am using default settings to the best of my knowledge.

Any suggestions welcomed!