That is the most anonymous way defiantly, http://www.vimeotomp3.com/ , http://www.youtubecomtomp3.com/ , http://convert2mp3.net/en/ and http://catchvideo.net/ these works great. The disadvantage in that method is that must wait for complete the download of a video if want to watch form the middle to the end for example , need more time compare with adobe flash plugin on TBB , but can’t have them all .
And a must if install adobe flash plugin on whonix and later uninstall it (dellete flash cookies):
My special thanks to Patrick and entr0py.