Are you wondering how you can create a screen cast to demonstrate an application you have been using and want to share with your friends? well it's not that heard at all, if you have CamStudio 2.5 beta . It is an absolutely free software with all the functionality you need. You may download it from this link or by visiting http://download.cnet.com/CamStudio/3000-13633_4-10067101.html?tag=mncol.
The Pros: You can pause and record , in capture fox (add ons of firefox) you can't do that. The Installation is easy, just download the 1.2 megabyte file and unzip it, you can also keep it in your jump drive (usb pen drives,sd cards etc). You can even transfer it to flash video format. You can enable auto pan feature which will track your mouse pointer and automatically capture that portion.
Cons: In order to improve the performance you need to have a good settings for both video and audio option. Please choose the settings options care fully.
Here is a sample video that I created with Cam studio (this one without voice, but you can create with voice as well) You may reduce file size by reducing region size and changing the video outpu format to flash(swf). If you have any problem operating this software you may write a comment here, I will try my best to give you a solution.