As to the question if it is Chinese or Japanese Giant Salamander, I can't be completely sure. I didn't see the original clip on TV to know if the narrator gives any specific information on the animal, or the other habitat, so I cannot say for sure. Anyone?
It is very difficult to differentiate between the two species, but I'm 99% confident if I saw the two side by side I would be able to identify them properly. The A. davidianus I have seen in person have been very gray, and more clumsy in appearance, and this holds true for many of the photos I have seen, but not always.
Within both species, there is much variation in head shape, and size, as well as the pigmentation of the blothces. But a majority of the Japanese giants have that larger muscular head shape. I think, and this is really quite anecdotal, that the species in the video is the Japanese Giant because of the very large head, and darker coloration (although the lighting to be sure of this is rather poor). Also, and again anecdotal, I am pretty sure it would be much easier to film in Japanese waters, than in Chinese waters. Both countries appear to be very proud of these animals, but so far, Japan is much more open and easier to work with from a conservation perspective.
That is my take on it, but I am certainly not an expert, just an enthusiastic enthusiast.