I’m not an expert, I only fly small piston planes, but watching the video the cowling has opened as they do when the thrust reversers have been applied, however the engines are dragging on the ground so I’d assume that forced them open. I’m not sure if opening the exterior would engage the thrust reverser (i.e. is the external mechanism tied to the internal mechanism so they move together, or do they move independently?), if not then we can’t conclude much from the video.