I was only to view the video twice and something went wrong with the plugin. I would have like to have seen something in normal speed and not slo-mo. I agree with the lower body assessment and I think that tempo is the missing component along with the hips being more involved in creating momentum. Tempo helps convert energy into rotational power and I think that’s one reason why you see the poor finish.
The other point is that the gloveside and arm side have a synergistic relationship and I love how they start out of the glove and the arm works well. However, I don’t see that relationship present at the end of the delivery.
I will attempt this without the technical jargon and hope it’s not lost in translation. The arm action movement originates behind the scap on the throwing side of the spine and at the sternum in the front. The glove side action originates on the other side of the “equator”. As we load the scaps, the glove side helps unload the scaps by involving the chest and helping pull the shoulder through while not blocking the rotational path set in motion. I personally am not a fan of the cue “closing the distance of the elbows”. Just my opinion, doesn’t mean it doesn’t help others, just not me. I see it being more of “closing the distance b/w the shoulders”. I am a believer that the arm loads by retracting the shoulders and unloads by protracting the shoulders. The glove side and chest are primary factors in the unloading of the shoulders, considering the arm and glove side are in a position to throw. You will see many guys that can effectively unload the arm action but do not decelerate properly, Verlander is an example. I see the glove blocking off the path of the arm just after release. I see the same thing here, but again I just glanced at the video a couple of times.
The second area was the lack of momentum created by the lower body as Slew suggested. Because of that I just don’t see much energy being converted or transferred up the chain. Many studies suggest that a primary issue of concern for labrum injuries are the hips and I feel this one of the obstacles in convincing myself of the pronating to decelerate, if the hips are not effectively decelerating or in a position to throw, doesn’t really matter because the cause/effect relationship will trickle up the chain, Bob Gibson is an example.
Trying this from my cellphone and it keeps me from being able to glance back over, excuse the rambling and mistakes, hope it makes sense.