i suggest going to http://youtubedownload.altervista.org/
its freeware and fully safe...and it also has an in-built option to convert the downloaded flv file to most popular video formats! i've been using it for a long time and have no problems with it at all. 
Thanks for the shout, Kaigan. My name is Sarah and I actually work with YouTube Downloader.
I just wanted to let you know that YouTube Downloader is in the process of transitioning to its own domain, The new site will have a very helpful how-to video, and also now includes information about converting to a number of popular devices (ipod, iphone) as well as popular formats (mp3, avi).
We will eventually be closing down youtubedownloader.altervista.org, but not for some time.
Best Regards,
Sarah