Yes, get the hips moving down and toward the plate first…I believe the issues CoachPaul mentions might be a reaction to not getting much of a leg drive. Without the leg drive to power the rear hip through and create the power into foot strike which then should move up the kinetic chain, he is pulling hard with his glove and head to create the extra momentum of rotation to accelerate the arm to throw hard. Leave the glove out a bit and use it to “block off” or change rotation to forward movement towards home with chest and head following chest.
AS far as the drive…I just see the leg collapsing and rolling over rather than driving forward towards the plate.
As for the lift leg, he does a pretty good job with it, but remind him that the lift leg is to be passive, not reaching out or kicking (karate side kick), because that can lead to pulling the back side off before it can drive or opening up too early, you need to stay in that back leg until the point you can’t hold it any longer. The front leg should get out far enough so that you are pitching against it, not over it, but don’t reach out with it until very last second.
Honestly, all that is a lot to throw at a kid, so I’d concentrate on leading with the hip and keeping a load in that back leg until he has to drive, don’t let the leg rotate under until he has created the push towards the plate. But in all good, I really like his arm action and timing from what I can see at that angle.