What? I watched, saw a flash, and suddenly she was going the other way. Then, I looked at the feet, and saw that they changed in the quick flash. It's not what you perceive it as, it really is when you perceive it. By the time you read that it means which hand is dominant, odds are, it's changed. As a human, if what you saw aligns with what bustin said, you won't double check. If what you saw didn't match up, you'll look again, and probably see the opposite, and then be satisfied.
This cake is a lie, and it didn't take much to notice that.
As far as her feet go, they get larger as they approach the center, and at the moment of crossing, they become small. So yes, this could be true as an illusion pertaining to feet, but it isn't true pertaining to the entire body.