An old friend of mine works in transit in Boston. He was actually the first person to see this now-viral footage of a woman stumbling onto the tracks in front of an oncoming train. Here's what he had to say about it, with the footage below.
I'm actually the first person who saw the footage, my boss asked me to head over to the control center and see if there was anything on tape about what happened. I'm not sure what I exclaimed in the middle of the control center when I saw it, but it was enough for every subway dispatcher in the room to stand up and look at me.