Did anyone ever figure out the culprit to this noise? I have the EXACT same noise coming from the rear passenger area, in the panel that the seat belt comes out of near the ceiling. The noise is within a few inches of the seat belt. I thought it was a vibration, but after shoving foam packing paper back inside of it with the hope of stopping a vibration (this did not help), I think it really is an improperly grounded wire. When I pull the panel out a few inches, it's clear there is some type of wiring inside this panel and I suspect the wiring is in there. The video at the beginning of this thread is absolutely the noise I am hearing. I direct messaged that person but never heard back to see if they every figured it out. Thanks everyone.
For me, the noise was coming from the seatbelt bracket in the right posterior rear seat area. It was making a constant click-clacking sound. If you're hearing something similar, it might be worth mentioning this to your dealership—apparently, it's a known issue with Bronco Sports. Hope this helps!