I like to download videos from youtube using the magically delicious DownloadHelper. Especially music videos. The only sad thing is that the video quality tends to be poor, and it can only get worse if you convert it to a less crappy format than the standard flv — such as mp4 for example.
But Youtube is being kind to us. Many, many videos on youtube, if not all, are available in a higher quality format — in fact, mp4, the format that is standard for things like iPods. The magic you do to get the higher quality is take the youtube url and add “&fmt=18” to it. That’s all. Just add that to the address in the address bar and reload and you will get a higher quality video, which you can then download with downloadhelper. You might need to change the .flv extension to .mp4 to play it back with Quicktime.
There’s also a thing in Youtube’s account preferences you can set to get higher quality stuff by default, but I don’t think it’s the same — I think (not sure) it gives you the fmt=6 version. (there are at least two different higher quality settings, &fmt=6 and &fmt=18 — I think the &fmt=6 is better than the default but not mp4-encoded like &fmt=18.)
There’s a greasemonkey userscript to do the fmt=18 for you.
UPDATE: if you see something in the downloadhelper.net menu called Video.mp4 that’s guaranteed to be the good stuff. I think it also shows up under other names sometimes too — downloadhelper sometimes offers several links to the same video so it’s confusing.
UPDATE: it ain’t just video. The audio is *noticeably* better in the higher quality downloads. Much crisper, makes the old kind sound muddy in comparision.