It's too bad we didn't hear about that Barnes & Noble system back then. We might have been able to help.

Be cautious when observing that there were hum bars in the video and that the hum bars bounced to the music, then concluding that the 70V system generated the hum bars. You are assigning cause without understanding the problem.  Maybe the 70V system was not the cause but something that happened (an incident) along with (latin "co," meaning "with") the other thing, making them co-incident. Coincidence really means that they happen at the same time but that you don't know enough to assign blame.  All the detective shows say they don't like coincidences, meaning they believe one thing caused the other or some third thing caused both.

It is often simple to erroneously say one thing caused another when the truth is that all we know is they happened at the same time.  Experimentation and solution can tell us if this is true.