Mark Rippetoe is the squat guru - go nowhere else other than his unrivalled primer, "Starting Strength"
There is only one squat worth squat - and it's the barbell "back" squat. The gym junkie guy is almost there, but still has the bar a little high, and has his wrists cocked. Like most poor form, this throws weight forward on the toes, and introduces knee strain.
He is probably squatting a little too deep in the demo - squatting deep is good, but not so deep that the lower spine starts to flex. The golden rule is that the entire spine is locked rigidly straight for the entire rep, if not the entire set.
Just sayin...