I've mentioned Keepvid before as a good way to get a backup of that perfect clip. I know some teachers are reluctant to use material from Youtube because they wonder if it will remain accessible from term to term or week to week. All it takes is one time for you to get burned (ie it's not there when you need it, or your school doesn't have enough bandwidth to show it or it's been blocked by your sysadmin) and then you're not so sure!
Keepvid gives you the option of downloading the clip, so at least you have a back-up copy, just in case. The latest cool trick is that Keepvid has now added a "bookmarklet" to their site. All you have to do is drag the little "box" to your menu bar (see graphic below), and then, from now on, any time you see a clip on Youtube you would like to archive, you click your bookmarklet, and "presto", the clip can be downloaded....so easy!
