Here is a link to a National Geographic North Korea documentary hosted by Lisa Ling. To watch the whole thing you will have to click on the other four parts of the documentary to the right of the playing video. It is a bit corny and I think some of the facts may not be totally correct, but it still has some interesting interviews and footage.
One thing I didn't know was that the US-South Korea forces sometimes use loudspeakers to send messages across the DMZ. The documentary also shows some fascinating clips of Kim il-sung's funeral. Again, it is definitely not a scholarly documentary or anything, but any sort of footage inside of North Korea is interesting to see.
I have also included a clip of a North Korean cartoon. It shows little kids using pencils as missiles against Americans!