here. I think this is legal, it says on the site that it's sponsored by YouTube and other well-known sites, and it was my computer teacher in high school who told me about it in the first place. The videos will be download like an Adobe Movie-file, so I guess you have to have Adobe installed on your computer for it to work.
Another site that I love, is Mp3-ify, where you can make YouTube-videos that you like into mp3-files. I guess I'm the only one who find use in this these days, because I'm the only one who prefers iTunes over Spotify, lol. But Spotify doesn't have everything, now has it?
Anyways, all you have to do is paste in the URL to the movie that you like, and then quickly download it to your computer. Tadaaaa!