He really is too cute. I don't mean to be a downer but I had a German Shepherd Puppy who started doing that at about 10 weeks old. We thought it was so cute until he didn't stop. He turned out to be a compulsive tail chaser. Not a good thing to deal with. I hope your boy just does this once in awhile. I would try to discourage him somehow. Just my opinion from past experience.
I agree with Rusty and Stickers mom. Try to distract your puppy from doing that as some dogs can get really obsessive about it. Our shepherd was doing that so much, we took him to the vet and it turned out his anal glands were full and once they were emptied he stopped doing it.
Very cute puppy!
We'll keep an eye out for the obsessiveness of the tail chasing... it sort of just seems like it's a puppy burning off energy but it's good to know it's something to watch out for. His anal gland shouldnt have to be cleaned out at 10 weeks should it??