you can always try those websites,the first one is recommended.
Code:
http://keepvid.com
http://www.clipnabber.com
http://kej.tw/flvretriever
http://www.kissyoutube.com
http://savevid.com
http://tunenabber.com
http://hold-tube.com/
http://keep-tube.com/
http://www.forinside.com/
http://www.freefileconvert.com/
http://vixy.net/
http://www.downloader9.com/
http://youtubedownloader.us/