When I first looked at the title of this video, my feeling was oooh this is not new to me. In the holy Quran, it is stated that
He has set free the two seas meeting together. There is a barrier between them. They do not transgress. (Quran, 55:19-20)
He is the one who has set free the two kinds of water, one sweet and palatable, and the other salty and bitter. And He has made between them a barrier and a forbidding partition. (Quran, 25:53)
Nevertheless, it is interesting to listen to the scientific explanation on why different types of sea water do not mix.