First of all, leakage between floors, what is the worst that will happen?
It must be a T. This unlikely good duct design (?). It weighs more and is likely sitting on the ceiling.
My concern is that you called this out. The contractor cut it out to look at it ( I wish I could get them to do that even when I “know” there is a real problem)! Nothing found! What is the adverse condition? Condensation in the cooling mode maybe. But not identified today.
Leakage between floors gets real big with time. Can lights will heat up the entire joist bay across the uninsulated ceiling.
Below is leakage (between floors) from yesterdays insp that is likely leaking between the boot and the register grill. Told the client not to get excited, but may want to take it apart and caulk the fitting.
I recommend caution with limited access issues like this. I would just identify the location for the client. If it molds, they can cut it out, fix the duct leak and refinish the ceiling (in this case, it was done without cause). I don’t think anyone will like this call after nothing was found!
Your camera can find some very minor issues that look HUGE! I have an electric heater running in my office and I can see the wiring in the wall and ceiling, all the way to the sub-panel! I smelled something burning, which turned out to be my wood stove. As I was downloading scans, I took a look around and saw it…
Just be careful with what you call.
Just because you can see it, does not mean it’s a problem.
Try posting scans here before you report. That was the intention of this section from the beginning, but few use it.