Why the Bengals? The Bengals?
Again, because it's not about the Bengals or this week's game. Any advantage gained there is incidental. It's about building info on a new HC from the McVay tree. It's for the future as much as anything else.
Taylor will be gone in a year or two in Cincy and end up the OC on a good team. This is just data for Ernie Adams to have at his disposal just in case he can notice something from the entire quarter worth of film of the coach on the sidelines.
The Patriots look for every minute detail. It won them a Super Bowl vs Seattle. They knew the play because they knew every tiny nuance.
Ernie Adams would watch film of McDermott eating breakfast, just to see if he could learn anything. 99% of this filming is probably useless, but it's about the 1 gem Ernie Adams can find. That's his job.
It's surveillance of other coaching staffs, plain and simple. 99.9% of surveillance is mundane and useless. Just part of the deal.