The stunt being filmed was not all that unlike others from the past when retired Cobra helicopters chased a vehicle down a runway strip, but in this case it appears that the single engine powering the Cobra gunship helicopter failed - and with the low altitude part of the equation, things went from bad to ugly in seconds.
(More after video)
While the low altitude likely played a role in the crash due to the pilot's inability to have time to react, the low speed likely also played a role - but a favorable one. Both occupants in the helicopter managed to survive without any major injuries - literally walking away from the horrific-looking crash.
It's safe to say that Cobra won't fly again, but as to the future of that particular episode it is unclear if Top Gear Korea will scrap the stunt completely or look for another helicopter