The Karate chop move is featured in Julius Richardson new book, Better Golf, a skill development. He notes he learned this from Australian,Peter Crocker. Interesting, but leaves a lot of unanswered supporting questions and comments.
Julius Richardson teaches an arm swing with a pivot move. Much like Brian's snapping the sugar off the arms. I think he is a wonderful teacher that trains the body and pivot before he allows a student to hit a ball.