The Girl Is Mine was released as a single first to get Michael played on pop radio in the States. After the "disco sucks" campaign, black performers rarely got airplay on Top 40 stations as they were considered disco music. That's why black acts (R&B) had to "cross over" to mainstream pop. At the time Mike was just considered a R&B act and R&B wasn't something that was taken seriously by the mainstream public. Paul was still popular at the time, so was a big help in getting that pop radio airplay. During that time, light rock and soft pop acts like Air Supply & Christopher Cross were big, so The Girl Is Mine fit in perfectly with that. As far as videos go, that wasn't a big thing then. MTV was just starting, so they hadn't yet killed the radio star, lol. Music videos have been made since the 1960s for some songs, but they were rarely shown. Before MTV, they were usually made to show in clubs & discos or as a cheap way to promote an act overseas without having to fly them everywhere which was costly.