They did go behind a plane. If you watch the video, you'll see one pass in front a few seconds before the collision. Night vision glasses won't pick up what is behind you, only what is in the direction of your field of vision.
The best way to describe the air traffic in this area ... as soon as one plane lands, another is seconds behind it. Not 30 seconds or more, I mean literal single digit seconds. Planes are taking off the same way - seconds apart. You have that commercial air activity going on, private aircraft activity going on, and military aircraft going on. Planes and helicopters flying at various heights and at all angles 24/7. At night, you have to add in the city lights and the glare of them bouncing off the river.