Shirley Halperin Executive Editor, MusicTo get a sense of YouTube global head of music Lyor Cohen, the person, imagine the type of brash, gruff New Yorker that might inspire a character called “record man” or “music biz exec” in a movie. After starting his career as a roadie for Run DMC, Cohen went on to head Def Jam Records in the mid-1990s and, over the next decade grew the label that would become home to the likes of Jay-Z and DMX into a formidable force in music.