If you want to create video tutorials for your site and looking for a good free and open source screen recording software CamStudio is right for you.
CamStudio is able to record all screen and audio activity on your computer and create industry-standard AVI video files and using its built-in SWF Producer can turn those AVIs into lean, mean, bandwidth-friendly Streaming Flash videos (SWFs).
You can record everything from your screen including your voice.
CamStudio is free and open source download and try it now!!.
Link : CamStudio