There is a good interview with Paul Fischer, who has studied this and related topics, here is one bit:
The way Americans are shown is equally counterfactual. There’s a long-running film franchise in North Korea that Kim Jong-il started called — depending on how you translate — Unknown Heroes or Unsung Heroes. It’s all about undercover spies, and the villains in every single one of them are dastardly Americans with bad hair and plans to kill children or poison people with AIDS. So there’s a sense in which the anger about The Interview being offensive to North Koreans is a little bit of the pot calling the kettle black. One of the weird things about The Interview situation is that in real life Kim Jong-un is this short, fat young guy who’s running a failed, bankrupt irrelevant state. I haven’t seen The Interview, of course, but from the trailers they make Kim Jong-un look like this broad-shouldered, badass cigar-smoking leader of an awesomely dangerous state. It’s actually a flattering portrayal. But it’s like with any kind of bully: They don’t get the joke. The fact that the joke exists is threatening.
There is a video example of Americans in North Korean film at the link. This is interesting too:
The country found The Interview‘s portrayal of Kim Jong-un to be hugely offensive. Are the Kims ever portrayed by actors in North Korea?
I believe there’s one film biography of Kim Il-sung — called either The Sun of Korea or The Star of Korea — where he’s played by an actor. Allegedly, this was a guy who they brought in and gave plastic surgery to so that he looked like Kim Il-sung and then, when they were done with him, they sent him off to the concentration camps. That’s the only time, because the thinking was, How do you have a guy play god? How do you paint god? So, with the Interview, the idea that there was an American playing the great leader, and playing him for laughs, and getting killed at the end — that just couldn’t be allowed.