Microsoft's Windows Movie Maker 2 is an easy video editing program. If you use Windows XP or Vista you have the program on your computer. If you have never used it or don't understand certain concepts like splitting a video or how to nudge a clip I think I have the deal of the day for you.
Atomic Learning has a free Windows Movie Maker 2 video tutorial on the software.
It covers the basics that you need to edit and produce videos in the .wmv (Windows Movie Video) format. The videos are in the Flash video format so most viewers should have no problems viewing the screencast tutorials.