I was going to flag this as not really being a HN story so much as something I'd expect to see go by on Facebook, but it did produce an interesting article link there.

I could see this going either way; a mouse could probably be trained to do this for a viral video. On the other hand, you can see animals get mental diseases known to occur in humans sometimes as well; an obsessive-compulsive mouse is also plausible to me.

(A disturbing number of "Look at my dog/cat/whatever doing this funny thing!" videos appears to my eyes to be the dog/cat/whatever having a seizure, for instance.)