The angles really shit, i think if you see that from behind dunne it would probably be given as a foul on Mcrorie. If you watch it back Mcrorie's arm is just reaching it's fullest upward running movement as dunne moves his arms out toward him. Mcrorie moves his elbow up to try and get it over dunnes arm and shoulder, cos he's trying to get past him to continue his run, and dunnes momentum takes his head into it. It's completely instinctive from Mcrorie and never a foul to my eye. I will concede I had to watch it multiple times and do a phoenix from the flames like recreation with my jambo neighbour to come to this conclusion though.