Got a fairly precise tag on that ABC recording: WXYZ (Detroit, MI), April 20 1986; broadcast started at 8 pm, but about an hour is missing, not including commercials.
Man that is something… I have the same Detroit broadcast recorded myself and complete (in LP mode IIRC), but the tape probably got pitched in the last few years since my parents started clearing out the house. Being that it was obviously different from any commercial video release I watched it quite a bit back in the day.