I think he looks pretty good for his age. I agree with the others, he can work on loading/hip/hand action in the mirror. My son is a professional ball player and he was home the last two weeks. I saw him swing to the mirror everyday.
Have him go to youtube and have him watch his favorite young players like Mike Trout or Bryce Harper. Have him emulate those players' swings while he is practicing.
He actually just adjusted his load the other day from a step to a small toe tap...he still is getting the feel of it, so we will see this weekend how it goes in the game. He does some practice in the mirror but it's mainly during winter. He's going to an instructor this winter, so that will help a lot too. Once I get a video of his toe tap mechanics, I will throw that up on here as well...thank you for all the responses.