This may not cause issues with light weights, but adding more weight, could cause some injury by having the knees bending in too much and hurting themselves. This could be fixed by shortening the foot distance from each other. His knees are at a good bend however, which is good because if you extend them too much you won’t have any power to push the bar up and if they are too bent, then you would be using more energy to bring the bar up. His hips are in a good position, they are pushed back and also pointed downward. This allowing him to get more power when he thrusts his hips forward. His back is in a neutral position up until his head, which is eyes are pointed straight forward. You want either a neutral spine throughout, or the head slightly up. A simple que to help this is to have them not to look straight forward, but slightly downward. His arms are straight with no bend, elbows pointed outward, and the bar is close to his shins. A good cue for how close the bar should be is it should almost or should scrape the shins as the bar is getting pulled up. Moving to the “extension phase”, his toes are pointed up which good, has a good hip extension making it easier to get the bar