The Real Ghostbusters, in its 4th season on ABC (5th overall---don't ask), were granted their only primetime special. The Saturday edition had expanded to an hour to give Slimer (Frank Welker) his own half-hour of comic adventures.
However, "The Halloween Door" is a half-hour in length, and, oddly, starts with a song. "Touchin' Old Magic", performed by the Ghostbusters themselves (Welker, Dave Coulier, Maurice LaMarche, & Buster Jones), before the drama begins.
Yeah, you're getting the "music video" twice. Can't be helped. This next clip is missing the opening scenes.
Coulier (Full House) was actually trying to do a Bill Murray imitation, rather than Lorenzo Music, who'd left to do Garfield & Friends. Apparently, Jones didn't sing after all, as Bus Boys frontman Brian O'Neal sang Winston's parts.