Ray Parker, Jr., before 1984, was known mostly for R & B/pop crossovers like "You Can't Change That" & "A Woman Needs Love", recorded as "Ray Parker, Jr. & Raydio". In 1984, Parker cemented his status in pop culture with the theme to "Ghostbusters", which would turn out to be his most successful hit, period. Parker hasn't been heard from much since then, though.
As you can see in clips from the movie, interspersed in the video, Slimer was introduced in the movie, leading to his (its?) becoming the team mascot in the subsequent cartoon series, The Real Ghostbusters (1986-91). The video features cameos not only by the film's stars (Bill Murray, Dan Aykroyd, Ernie Hudson, & Harold Ramis), but also by the likes of Chevy Chase, Irene Cara, John Candy, Carly Simon, Peter Falk, Danny DeVito, George Wendt (Cheers), and Al Franken, who back then looked suspiciously like he might have been separated at birth from Rick Moranis (who appeared in the movie as lawyer Louis Tully).