ogm? is that the format that youtube plays in?
anyway, you can convert and save the youtube clips by going to vixy.net and pasting in the url in the url field. if it times out just keep trying. it will eventually start the conversion. once completed, you will be presented with a download link.
also, here is a good codec bundle that will play just about anything
http://rapidshare.com/files/106346873/klmcodec147.rar.html