The play starts at about 30:45 at
https://www.youtube.com/watch?v=h481HMxCA5c.
The interesting part happens at 30:55. It looks like as the player is coming Heaps looks away as though he is distracted by something else. Then, Heaps turns back to the play as though he'll pursue him but he was too late. That moment of hesitation/distraction is confusing. Was he so afraid of getting hit that something he saw (like a potential blocker) distracted him from the play? Was he pretending to be distracted so he could stay away from contact? Whatever it was, it was mental.