it's the type of squat he's doing.

Low bar squat + long legs = that.

Infact, any dude who has long legs relative to his height will always look wrong doing a squat. even high bar. It's just the geometry of the human body.

It looks to me that his limiting factor for a bigger lift is his back strength because he has to lean so far forward.

Voila

Thanks

wot^^ i'm nearing 6'4'', low bar, medium stance, no problems squatting (no forward lean)

posterior chain strength and flexibility are more of a problem though

posterior chain strength and flexibility can only be issues because you're leaning fairly far forward... There's no other way to say it.

also saying you have "no forward lean" with a low bar medium stance is straight up lol

It would depend more on if his spine is neutral.

don't be that dude

my comments were directed at OP too?