I use to work with two baby hippos that did that while they were in the water. You could raise it higher nad higher and they would bob to meet it. I never did start the hose once without Mary making a beeline for me. SHe didn't like to fight it like that, she would just lick and lick until your thinking surely she has had enough and make her stop. make some mock bites at it with a lot of tail wagging. SHe thought the hose was just for her.
I had a lab that loved to play tether ball. If the wind blew it he was on it fast. I don't think that is really any different. SOmething to do..something to be interested in. I thought it funny that the one by the steps got the most attention but the others were not left out.
I had a Border Collie growing up that was equally obsessed. She would chase the jet nozzle spray on the garden hose until she reached the nozzle, then have a sneezing fit before starting again!
IF VIctor hit a field of butterflies he would do it for hours too with glee. I didn't see real anger in there, they didn't race like they were after prey, they ran like they were goofing around. Mine will play rest play rest for hours too if there is something they love doing about. I just don't think it is ocd at all.