I call that hair-holding, not hair pulling. At no point was he dictating how far back her head was, because his grip on her hair was weak and just for show. Put your pants back on fella, I'll show her how it's really done.
Doggy with hair pulling is my all time favourite. It invokes in me deep, animalistic, primal instincts . And I love to watch it how other people are doing it, I am horny hedonist, very voyeuristic. Like this!