I don't remember what channel it was on but I'd guess that it was most likely 5 or 20. I remember seeing the commercial in the afternoons after school so I would not have been watching channels 4,7,9 as they were mostly soaps and talk shows which I didn't watch. At the time I was living in the Washington DC area (and still am).
I have searched for this commercial several times and, until now, have come up with nothing. I'm thinking it's from the early 70s, but hey, it has been 40+ years.
What I remember most is the line:
"Sez-a-who? Sez-a-me!"
I'd love to see it again.....