There were a lot of headshots on god players who shouldn't be getting HS that often, but I don't think it's possible to make the HS hitbox bigger. The hitbox switches turn all bodyshots into headshots, and that clearly isn't happening here.
However, this is [ED]Nanobot, and I've suspected him of cheating for some time. I played him once when he was anonymous and he was very, very accurate with the AR. When I told him that I knew who he was, his accuracy dropped considerably. Sadly, there just isn't enough evidence to count as absolute proof of cheating.