Basically It's really stupid to use any data before the 30-40's regarding blood pressure and the kidneys because we didn't know shit back then. What I recall from my classes, the current model is not even fully understood.
The conclusion he makes, for what reason the baby died for at 1:40 is so awfully forced.

The kidneys are really good at balancing the levels of salt in your body, and especially to reabsorb it. He talks about some physiological process salts are involved in, but they don't get better if you consume more salt.
The South Korea example is bad, because 4000 mg is close to nothing compared to what for instance Denmark consumes, around 9000mg. There are plenty of factors why you get coronary heart disease, not just salt.