First video could be stress from the cold water.
Second video, seems to be normal behavior for them since mine do it too. I have 4 at about 4-5 inches and they do that pretty often. BUT I don't think its territorial behavior, more of a hierarchy since all 4 of mine school 95% of the time. I never had CAE (nor do I want any with my current stocking), but SAE keep to themselves and like each other's company (as long as the boss isn't challenged!) very much. At least, that's my experience with them.