HOw you do that? 
No joke, I have wanted to save several youtube clips of music videos but have never been able to do it.
If you use Mozilla Firefox as a browser it is super easy.
I'd highly recommend downloading it, as it is a great browser
Anytime you come across a vid you want to save the download helper rotates up in the top of the browser, and you just click on it.....the video is saved
https://addons.mozilla.org/en-US/firefox/addon/3006 Youtube vids are .flv files which a lot of media players wont recognize.
You can easily convert the .flv files to .mpegs with this program.
http://winff.org/html/ There are MANY ways to do this, but these two programs are definitely the easiest way I have found
