Tools/Apps that I have used before:
1) MS PowerPoint: Using Narration Function and save the file as video format. The online tutorial can be found here
2) MS Media Encoder: Online Tutorial: https://www.youtube.com/watch?v=Rsj8oz0_JJI
3) Screen-o-Matic: easy to use but restricted by 15 minute recording
4) Cam Studio (http://camstudio.org/): Open Source Software that
5) Camtasia (http://discover.techsmith.com/): Inexpensive software that can create teaching package
6) Beside YouTube, screencast.com(http://www.screencast.com/) is also a good site for streaming and distributing your screencast
Below is how you can
http://www.screencast.com/t/i2JrEJZVKYa