North Korea is undoubtedly one of the most closed off countries on earth. Few Western reporters are on the ground in the country, and its own media efforts are rarely taken as anything other than propaganda.

Not only does this mean that poorly-sourced stories about execution by dog make headlines around the world, but, more importantly, it also means it's exceptionally difficult to analyze the changing state of domestic politics inside the country. If outsiders can't accurately get a feel for the situation on the ground, it can be difficult if not impossible to know how to work with (or against) the North Korean government.

One man who is trying to gauge the situation in the country is Jiro Ishimaru, a Japanese journalist who works with Asia Press to operate a network of secret cameramen and women inside North Korea. The leaked footage acquired by Ishimaru shows subtle changes in the country. For instance, in the footage below, women who are accused of illegally running businesses or breaking the rule on females wearing pants angrily accost the soldiers who are targeting them.

It's remarkable footage. Don't forget, North Korea is a country known for its horrific political prison system. Both the women in the video and the person filming it could be jailed for violently defying authority.

Ishimaru's footage forms a core part of an hour-long Frontline documentary titled "Secret State of North Korea" due to air on PBS tonight. The show's director, James Jones, has told Foreign Policy magazine that one of the most startling moments — when a once-fervent North Korean state supporter called Kim Jong-un a pumpkinhead — didn't even make the cut. For Jones, these are just some of the many examples that seem to show North Korea is changing.

For more information on the show, which airs tonight, check PBS. Check here to see when the show airs in your local listings.