For the Pc there is CamStudio, which is opensource and therefore free.
However, there doesn't seem to be an equivalent for Mac users. I have tried using CamStudio on my Windows 7 running under Parallels, but it's far too cripplingly slow, and the presentations are all in the Mac (Apple Keynote).
I tried a couple of others, but they either didn't pick up audio, or are for desktop screen grabs only.
You can use Quicktime, but you can't select a part of the screen, only the whole screen. :confused:
Any Maccies out there who know a solution?
Please don't suggest "buy this or that", as I said, the funds are tight - very tight.