http://www.youtube.com/watch?v=*******

Change to

http://cache.googlevideo.com/get_video?video_id=*******

Example :

http://www.youtube.com/watch?v=vt4X7zFfv4k

Change to

http://cache.googlevideo.com/get_video?video_id=vt4X7zFfv4k

And Save As *.flv

Thanks......