I coached HS ball for several years and I would never mess with a kids swing if he was making consistent and strong contact. I worked a few camps with Tommy Walker when he was the HC at Samford University. He used to always talk about having the hands quiet, in a "punch" position like a boxer, with the elbows tucked and not look like they had posed for the Little League trophy!!!! A few kids, I had to reposition hands, elbows, feet, etc.
As for the video, I wish the kid was swinging a bat that wasn't longer than he is tall!!! The proper bat might help that speed and those wrists!!