Assuming the fish is the size it is claimed (and I don't doubt that after seeing the hand for comparison on the first vid) then I would say that is a 6x2x2.
You have to remember there are some pretty big fish in there, so the tank will look smaller without an external reference. Watch the first vid again and you will see a hand go up against the black shark to get a sense of scale.
Well that would make it a 125G tank wouldnt it?