What is lip dubbing? Lip dubbing is when you record yourself singing a song then synchronize an mp3 of the song to your video clip in iMovie (or any other video editing app). Vimeo users have been posting their own lip dubbing videos with a lot of praise. Recently the staff at Connected Ventures (the fine folks behind Vimeo, College Humor, Busted Tee's etc.) posted the best lip dubbing clip of all. If you do not crack a smile while watching this something is wrong with you.