Good weight too
Tell him to keep doing what hes doing
Btw, he should get some better shoes because it looks like his feet lose their arch and roll to the inside. That could cause knee problems when the weights get heavier.
No need to get lifting shoes yet, something like Cons or Adidas Superstars or Sambas will do.
I could be wrong on the foot thing (hard to tell from the angle), but he should get better shoes anyway.
You could have him do some box squats to teach him good form.
I do not mean box squats as in the Westside style, with super wide stance and almost vertical shins. Thats for geared lifters in multiply and shallow depth regulation.
For raw lifters, the box squat is often done as normal squats, with shoulder width or slightly wider stance, a slight pause on the box while keeping all the tension (not relaxing and sitting down causally on the box), and then letting the legs and hips do all the work to get back up. No "rocking" or tliting motion to get off the box and stand back up. Focus on sitting back while pushing the knees out to the sides and opening up the hips.
I've been doing them for 5 weeks now on my new program to learn better form and it has worked well.
Go really light on those. I do 3-5 sets off 5-8 reps with 50-60% of my 1RM squat and thats pretty tough.
It should look like this: