I use vixy.net but there's loads of stuff you can use if you google youtube ripper. I like vixy cos you dont have to d/load any software and its easy to pick what format you want to save it in.
I do it through Real player - in the top right corner - you type in the you tube web address and it works like google - you can then go into youtube, find your video and right click on the screen and it will give you the option to download to realplayer. there might not be what you are looking for still on there after yesterdays news - my oh went to get some led zeppelin ones he hadn't downloaded and they were all gone.