Doing a install in a maintenance shop, needed a workaround to get below the ductwork, the boys in the shop had me set up in 20 mins with this, nobody there cares about aesthetics and works well.
And looks better than mounting the cam directly to the bottom of the duct, with the bare cable dropping from above the duct to the bottom of the duct.
And a clever combination of black pipe (plumbing) and metal junction boxes (AC wiring) for a camera (low-voltage)
Correct on the outdoor round box, I have a Jig setup for the covers, I drill 2 holes for the cam holes and use the cover with a longer screw for the third cam hole and a hole in the middle for the wires, depending on the location I sometimes pop a small hole in the bottom for a moisture drain. I use the stock gasket that comes with the outdoor box and dab a little clear silicone around the top to keep the water out in case the gasket leaks.