If you know very little about baseball, repetitions and video won't help. He needs to learn the proper techniques first, then repetitions will reinforce and video will help him keep things on track. I know a lot of people say wait till puberty hits, but think it's important to step on to the big field with the proper fundamentals. The switch to the bigger field, BBCOR bats and playing with bigger kids can be daunting for a kid who doesn't have the tools to compete, doesn't know how to get better, and feels behind the 8-ball. It may seem like wasting money to get ahead of this curve and for some I'm sure it is, but for many kids if they are psyched out and don't feel like they can compete it's tough to recover from. I started my kid with a hitting coach at 11/12 years old and really glad I did. It helped him understand his swing and he understood what it took to drive the ball into the gaps. When he stepped onto the 60/90 field he was ready to compete.
By video of course I mean side by side comparison with mlb player of choice. Even if you have limited baseball knowledge you can see what your son is doing compared to the pro. Half these former pro ballplayers teach things they never did. Many have no idea how they hit the ball they are just really good at it. I would like to think the 'dumb jock' is an unfair stereotype. But assuming cause a guy played minor league ball for a few years he is a hitting or pitching expert is also an unfair stereotype. It all depends how much of a student of the game they are. And anyone can become a student of the game if they choose to. No need for instructors.
You're a coach and you have the skills to do this, so your fortunate that you don't need to hire a coach. I agree there are good coaches and bad coaches, but I'd say the worst are those that have zero experience and know next to nothing about baseball - ie, the OP (per his own comment). Unless the OP has a half dozen sons and is willing to do on-the-job training with the first couple until he figures it out, I stand by my recommendation.