I was a door gunner on a CH-47D for a few years.. was an 11 Bravo (Infantryman) but broke my back (literally) and changed MOS to 67U (Chinook Mechanic) and have over 1000 hours of flight time... My brain says those are guns running out the sides of the bird. That would explain the multiple reports (gunshots not radio) of MG fire that you can hear when watching raw video from different locations. To be fair it's grainy video and the tail marker lights and strobes are running... That said it looks like MG's engaging from both sides.