The youngster looks strong. From a pitching coach’s point of view, I would like to make an observation of how I would coach a pitcher to pitch against this kind of batter’s motion:
THE PITCH - if this batter’s standard hitting style is consistent when reaching for the fence, not place hitting, every time he picks up his front foot like the way he does in the video, I would expect my pitcher to bring a hard breaking slider, high inside.
WHY - the breaking action of the slider takes advantage of this batter’s temp off balance stance when the front foot is raised like he does in the video, and the high inside takes advantage of his arms placement.
If this is your boy, the next time he takes BP, ask his coach to instruct one of his varsity pitchers to bring hard breaking sliders, high and inside, and see how his quality at bat nosedives.