I don't know how accurate the various videos are, but if they are, the Delta pilot was probably able to visually see the plane on the runway ahead, perhaps even

I don't know how accurate the various videos are, but if they are, the Delta pilot was probably able to visually see the plane on the runway ahead, perhaps even before the tower noticed it. The plane seems to begin decelerating very early, before I'd expect the "cancel takeoff clearance" message to have been fully understood by the pilot.