CONV. - Convert YouTube video to MP3, GIF or MP4
Bizdownloader - Bizdownloader is Video Downloader website from top social networking websites like Youtube...
Downie - Video download for OS X. Downie supports at this moment over 1,000 different sites.
Transcoder - Transcoder is a free command-line-based video converter that allows you to convert any size of video into a range of audio and video formats.
Yout - YouTube to Mp3 Converter
Wondershare UniConverter - Wondershare UniConverter (originally Wondershare Video Converter Ultimate) can convert any video to over 1000 formats at 30X faster speed without quality loss, burn DVD, compress/edit/download/record videos, transfer files to devices.