Camstudio is the only open source screen recording tool I have used ever. And needless to say it does it job easy and without a steep learning curve. Select output format avi/swf, press record, select region and press stop - thats it you have got your screen video in swf/avi format. The setting, most of them are pretty self explanatory if not completely easy. The only gripe if that is any, is that it does not look as sleek as its paid counterparts!

One very nifty use I have used camstudio is for making a copy of my web based training. Since there is no way to save a online browser based screencast I used camstudio and was able to save it as a audio/video movie!