Every plane is different and you can certainly get stuck with the gear up or unable to support the weight.

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.

You also generally don’t raise the gear until you have positive rate of climb, I only fly small planes, but the principal should be the same.

This plane looks like it’s going way too fast and not in landing configuration. Maybe they couldn’t get the plane into landing configuration due to some failure, that would require them to keep their speed up (flaps/slats reduce the landing speed), but even then it looked like they weren’t slowing down, so maybe they were still under power?