I see a few things, at least I think I do.
1) He looks a little off balance i.e., he seems to lean back towards first but that's a little difficult to determine because the camera angle is taken from the third base side. Pause at 3 seconds and see if you see the same thing. Looks like he fights to get back into balance. Also note the back leg flex...he may want to stand a bit taller.
2) He appears to break his hands a bit too early. He looks a bit rushed and out of rhythm.
3) Maybe opening his front shoulder too soon which is indicative of being out of balance and rhythm.
With said, looks like you have a lot to work with and just a few minor adjustments. Can you tell us where the majority of his pitches end up?