It really does matter when the words are longer. With short words there’s a limited number of permutations, and letters can’t move far from their real positions

It really does matter when the words are longer. With short words there’s a limited number of permutations, and letters can’t move far from their real positions. And that demonstration didn’t even attempt to fully scramble the internal letters, it was a rather cherry-picked example. In a language like English with a lot of short words it works better than in others.