Screen recording question - webinars/online tutorials

[Rolliesworld]

I would like to record the occasional live webinar for offline viewing. I also bought some online video presentations that do not provide download of the files, which means it costs me download bandwidth each time I watch them (I am on a limited wireless plan).

What free screen recording software would you use? I downloaded Replay Video Capture but it is a trial version only and does not let me record more than a few minutes. I have read about CamStudio which seems to be good, according to some discussions here on the forum (with the correct settings).

Is AVI the standard file format? That is a hell lot of data ... should this be converted to another format for my purpose (watching offline for myself only), or is there another format in which it can be recorded?

I have also tried a few other free applications, but I am either not happy with the quality (delayed movements in video) or I did not manage to record the audio of the videos/online presentations.

Any suggestions or tips would be appreciated.