I just wanted to post my own testimonial of this method.
I tried it on some broad jumps and on some SVJs and I have to say that it does improve you to get higher. I still try to incorporate is into RVJs but its hard to check whether I do or not.
Conclusion: Everyone who has not read the article and tried it, DO SO NOW!
I have noticed i do this when i sprint and jumping. When sprinting my right hand on the down swing rotates as it goes behind me almost as if im reaching behind to catch a baton. i always thought it had to do with keeping my hands relaxed as i ran, and so it had a tendency to wind. i believe personally it might be a natural way to keep your body loose so you dont tense up because as soon as you tense up and try to go over 100% thats when form breaks down (dont clinch fist tight or tense hands while opened)