i like video download helper for firefox its easyer and it can convert it for you after youve dll'ed it
and for youtube you can just put pwn before it and it will come up with lots of differnt links EG.
http://www.youtube.com/watch?v=EK2tWVj6lXw
http://www.pwnyoutube.com/watch?v=EK2tWVj6lXw