This one is a bit of a head scratcher. Watch this video. You can stop it wherever you like and count the squares however you like. Still, if you are like me, in the end you will find yourself being confused. How does it work?
I think it is a version of Curry's Paradox. In this case they have cleverly put it together in a way that divides up the squares in a way that allows them to change size without changing the number of squares. If you look closely, you'll see that part way through there is a video edit and the squares don't quite fit together as they did in the beginning. In fact some of them aren't squares at all. The fact that the illusion relies on some video editing is a little disappointing, but still, it's well done... I must say. Take a look at the videos below to see what is going on.
Here is a version of the problem
And the solution
Another version... (sort of)