1960s engines are engineering marvels compared to the nightmares of needless complexities that have been added. Glad I chose an S type over an F. Not any more fun to work on but the ride is worth it.
I had a water pump replaced on my 2016 f type and after the replacement there was a leak. I have taken the car to 3 different places and they are all trying to charge me $3200 just to replace all of the hoses instead of looking for which on is actually leaking. I know it shouldn’t cost that much to just replace hoses. After watching you video, I’m guess the radiator hose is probably my issue since you stated that that hose should be replaced when replacing the water pump.
I had a similar issue when we replaced our water pump on the F Pace (same 3.0 L engine if a V6) and the cause was the o ring between the water pump and the outlet tube he replaced just behind the water pump