Is there some sort of a conspiracy here? The model is rotated anti clockwise and there's no possible way for an animation to magically reverse itself using the power of your brain. Is there an internet joke somewhere I'm not familiar with that I've fallen for?
I think its the background color being a light gray and the model completely black making it look like it's flat and 2D. Have you seen the picture where you first look at it, it looks like a young lady? But when you actually look at the lines you notice that it looks like an old lady too.
If I had the time I would examine the web page source to see if there is a yo-yo script some where, or it could mean that I use each side of my brain every 30 seconds
I had my sister look at it the same time I was and when she said it had started going anti-clockwise it was still going clockwise for me. So I don't think it has a script in it. If there was thats one unreal script.