Two things stand out that I will mention in a minute. If you pause the video, frame to frame, he has pretty solid mechanics. Does he ever complain of bicep pain? If so, it's because he isn't finishing with his arm. It looks like it never really gets straight. The second thing is he is "walking through" his follow through. Look at glove hand pulling through and not staying over his left knee. The push off foot passes across his stride foot. Other than that, he is pretty clean. Keep up the good work.