One I have used which creates a video from a whole screen or a window, or a user definable area is Autoscreenrecorder all one word. It should Google OK. It seems to work well enough - I have made several simple videos of the Tiger. It creates AVI files which get quite big, but I haven't yet looked for a utility to compress them any smaller. Have you tried doing voice overs on videos? No-one seems to, so I wonder if it is possible/difficult?