That's very cool. I taught my brother at Christmas and despite my being right handed and him being left handed, he was a natural. I wanted to strangle him, it was so easy for him. He kept saying, "I don't get it, I don't know what I'm doing" and I kept saying, "Well, you just did another perfect stitch so just keep doing that."
I think if I had sent him home with some needles and yarn he would have kept up. He's mentioned it a few times since, and when he said he wasn't sure if he could even remember how, I gave him this website!