Looks to me like a Spider with a bad case of the "wobbles". If that's the case then it's actually pretty common among spiders. It's not for anyone to say from a few pics that it could be anything else. IBD can only be determined via necropsy. I'm sure others will weigh in here on this, but it looks like the wobbles to me. You will also see it called "spinning". Due a search and you should find other pics and videos with examples.