Don't be an idiot
As others have mentioned, the people of North Korea have been ruthlessly repressed for decades. It's easy to mock this kind of video from our safe and comfy seats, but the fact is that these people have been told from birth that their "Dear Leader" is, literally, a god. As preposterous as that sounds to us, it's a totally different perspective there.
It's easy to feel superior when seeing something like this. However, it only takes a moment's thought to realize that we should feel pity for these people, not scorn. I know you're probably only making a joke, and not really commenting on these people as people per se, but try and show at least a bit of compassion.