CamStudio is a free screen capture program (although the developer welcomes donations). It is, in my opinion, the best of the free offerings.
One of the problems with Camstudio is it has a 2GB file size limit and it records avi files (just about the largest of the video file formats). This has meant you can’t record more than about 15-20 minutes of video in a single session unless you tweak the settings, and if you go over the 2GB limit the whole recording is lost. From a learning and teaching perspective this is OK because 20 minutes is probably the upper limit anyway (1o min is probably better).
The problem is if you are recording a live presentation you don’t want to stop your lecture and reset Camstudio every 20 minutes. Well there is another option, using a different video codec. The developer of Camstudio recommends xvid which you can download from here.
I have done a few tests
- 1 minute using the default Microsoft codec = 40MB.
- 5 minutes using xvid = 36MB
The quality is comparable, in fact the xvid might be better, which means an hour lecture would only create a file size of about 450MB (instead of 2.4 GB which would crash the program). Once this is converted to a 640x 480 (260 BR) MP4 you’re looking at a usable hour video with a file size of only 160 MB.
As I said, I think shorter is better for screen cap videos but if you want a longer video, xvid looks like the way to go.