That sheathing that is dripping is located right under the plywood layer. the plywood layer in some areas is completely soaked. Assuming that this issue is from the condensation, and that the plywood has been soaked for a while. what is the best way to dryout the "in-between" layers? the first layer above the joists are dry. it's like the wet plywood layer is "sandwiched" between two rubber roofs, and im not sure how to dry that part.Difficult to really know what is occurring there. From the video it looks like that piece of sheathing is saturated. When the roof heats up and expands slightly that may provide a better channel for any trapped water to flow. IIRC I believe you said that this area is downhill of the supply duct, so it is could be condensation collected from the days before.
That area of the roof will need to be replaced at some point. Until you get the ceiling dried out it may be difficult to really pinpoint the source. Even if you can not totally remove those boards directly around the supply duct it might be worthwhile to carefully cut or drill a hole into that layer without penetrating the roof to see if you get a more immediate flow when the AC is on. Of course it is up to you to decide how far to continue probing, I don't know what might become too destructive in trying to seek out the source. Whether it makes sense to first try and add insulation to see if that works. Though it seems that this whole section of roof may need to be replaced sooner or later.
If I just leave it as is and close everything up with sheetrock and insulation, I feel like the water will never go away. should I close all the windows in the room, and just run my dehumidifier non stop all day long for a week straight? or what do you suggest?
I actually stopped using my AC for the last couple of days to see how the dripping goes. unfortunately today is a rather cool day (rainy), so I based on my experience of having the water drip in the late afternoon when it's hot and sunny, I don't expect it to happen today.
That said, I agree that this roof will have to be replaced, and I plan on doing that once I have found the source of the leak. I would hate to spend all the money to replace the roof and still run into the same leaking issue because it was not a "roof" issue.