That was a good video. I'll bear that in mind next time this comes up. It came up the other day on another thread, and I struggled to give an answer, see this post and this. Also check out photon effective mass. IMHO the main thing to remember is that for a photon E=hf applies. It's a wave. Not some billiard-ball thing. It takes all possible paths like a seismic wave shakes all the ground.