Hard to tell from this end of the wire, can't quite hear it.
I would lean towards a vacuum leak but again without being able to hear it's hard to say. Maybe a ruptured diaphragm in the vacuum advance canister? I had that happen but I could only hear at high rpm. Maybe a leak around the carb baseplate. You can use a propane torch to track a vacuum leak. Turn on gas, don't light it, and shoot the gas around the carb base and other areas you suspect. If the engine idle changes you found a leak.
I have a stick so don't know much about the flexplate and trans. You could pull the inspection cover and make sure all the torque converter bolts are tight.
Good luck and let us know what you find.