I think your site idea is an excellent one. I would be quite happy to make some screencast tutorials for it. and there is no need to worry about hosting as these screencast would be hosted with showmedo or blip. http://dai-videotutes.blogspot.com/
screencasts are hosted on blip.tv and used in my blog. So no need to worry on bandwidth of screecasts. So long as you are not expecting miracles on the graphics front only now learning to do graphics on a computer.