Maybe it’s from Night Tracks which aired on TBS?
The Los Angeles market had two local music video shows I know of that often played stuff MTV didn’t. Other large cities may have had something similar?
I remember Night Tracks-- that could be it.
The NY area had a show called “New York Hot Tracks” hosted by Carlos DeJesus that showed Top 40, but mostly R&B/Funk stuff…a lot of Prince (lots of clips on youtube).
Have you seen the new documentary material from the 2015 BTTF blu-ray release? I have the 2010 one, but I’m just curious if that “rock n’ roll” bit ever made it into any of the newer documentaries. You can see how when they shot it they may have been thinking that it kind of dovetailed the earlier scene in the film when Marty blows up the amp.