When holding the athlete's elbow, it doesn't have to be a tight grip. Even holding with one finger gives the athlete the visual and feel they need to keep that throwing elbow back.
So the big issue here is that the elbow is supposed to lead the arm. Watch any high level throw. Watch a baseball pitcher. The elbow leads. The elbow leads in both the Before and After videos (and her mechanics are better in the "Before" clip).
The elbow leads but not how she was doing it. She was losing all power by pulling her throwing elbow forward at the same time as her chest. I do watch high level throwers and their throws confirm all that I spoke on.
JD maybe referring to arm layback when pitching or throwing which does show the elbow leading. However, if the elbow leads the chest/head before arm layback occurs then that is the "shot-put" that megan is fixing in this video. I think Megan's drill emphasizes on hip-to-shoulder separation and delaying the elbow untill trunk rotation starts by someone holding the elbow temporarily. I've tried this drill with my daughter and it had some success, but not 100%, so it's still an on-going process. Thanks Megan !
I will try this with my beginner 9th graders in the South Bronx. Can I send you a video of my main pitcher who was a beginner last year and worked her butt off to be a legit main?