The cat guess the right shell that the ball is under, but the trick is done wrong. The way the trick is done on the streets, usually with cards and picking the right card, involves a sleight of hand trick most humans can't see, though to be fair a cat would be more capable than a human if it could have an understanding of the game. Humans can train their eyes to see through it too, but the ones that do/can are somewhat rare
The ones that can learn to see through the trick are rare? Isn't it possible for any human being with average intelligence to learn how to see through sleight of hand? You just have to know what to look for or what to look at.
Its not about intelligence, its about having eyes fast enough. The thing about the trick is even if you know it, they might use it and might not, so you have to have eyes fast enough to literally see which it is