He has good timing with his FH, steady Agassi-style backswing and follow-thru, and consistent contact point. His left hand crowds a bit when he swings through the ball, but overall it's pretty good above the waist.
One issue is that he doesn't really put weight behind the shot. (Usually a sign that the legs are not involved enough with the unit turn and stroke.) As a result, he tends to wipe on the contact point without really driving through. You'll notice that he doesn't have very good depth in his rallies.
There's two things that can help.
1) When he's practicing his swing, have him stand on just his right foot before he initiates his unit turn. On just that foot, have him go through the entire swing only landing his left foot when he's swinging through. Doing this a few times retrains your muscle memory to use your legs as you initiate the unit turn.
2) When he's practicing rallies, as you begin your stroke, imagine that there's a hand pressing against the back of your head (square to the back fence.) This teaches you to always shift your weight as you initiate the unit turn. This also works when practicing serves.
Directory of Tennis Warehouse Clubs (courtesy of Mountain Ghost)