Google’s been doing it for awhile (allowing you to download the movies) but there isn’t a good way to do it with youtube, until now.

The DVD Help forums has tutorial up on how to go about this. You’ll need Firefox, VideoDownloader Extension for Firefox and MediaCoder. Here’s how you do it.

1) Download and install all of the free tools listed above.
2) Go to a site (such as Youtube, MySpace, GoogleVideo, iFilm, etc.
3) Search and find a video you would like to keep.
4) Click the VideoDownloader Button in the bottom right part of your Firefox Browser window.
5) A window will pop-up. Click the button that says ‘Download Link.’
6) Click ‘Save to Disk’ and then click ‘OK’ in the ‘Downloads’ window.
(NOTE: If the file you download does not have the extension .flv, then rename the file and end the name with .flv)
7) Start up MediaCoder
Drag and Drop the .flv file(s) into the large white area
9) Click the ‘Video’ tab in the lower left-hand section on the window and select ‘XviD’ in the ‘Format’ drop-down menu.
10) Click the large ‘Start’ button (third from the right at the top of the window) to begin transcoding the video(s).
11) Once a window pops up saying that the transcoding has completed, then you are done!

And if you’re completely lost, the tutorial provides pictures as well. (Now for the part I want to add to this) If you don’t want to use Firefox (Heaven Forbid) or you don’t want to install the extension (a more likely explanation), you can go to the Video Download 2.0 and enter in the address of the video you want. All the extension does is save you that step of entering the address.

How To Save YouTube, MySpace. etc. Videos As AVIs [DVD Help via Digg]