Like most manufacturers, DJI tests its products before they go out the door to ensure as much as possible that they’ll work as intended. They can’t find every fault, but if they do spot an issue, they can remedy it before it’s sold. Unlike most products, most of DJIs can record video. Testing those recording features, and drone gimbals means they have to shoot footage.
Occasionally, some of that footage slips through the cracks and gets shipped out to users. I’ve built drones before, but I think if I had to build them all day long, and only be involved in one small step of the process, I’d probably end up as bored as this guy.