the article gave me this:
java script:if(document.location.href.match(/http:\/\/[a-zA-Z\.]*youtube\.com\/watch/)){document.location.href='http://www.youtube.com/get_video?fmt=18&video_id='+swfArgs['video_id']+'&t='+swfArgs['t']}
Just create a bookmark, and set that javascript code as the URL. When you're watching a youtube video, just click the bookmark you made, and it should initiate the download manager of whatever browser you're using.
I know it works in FireFox, and I think it works in IE too, but I'm not sure.
It's pretty handy if you ask me. No crappy software to install or anything.
It saves the file as an MP4, by the way.