The most plausible explanation that those people who escaped NK were sentenced for something else and use excuse of watching foreign films to look good to Western researchers. I believe that media landscape is restricted in NK, but getting a death sentence for a watching movie? No way it is possible.

Why do you think that is the 'most plausible explanation'? NK meets the simple test for evil dictatorships: do they need to use fences to stop citizens from leaving? Yes, NK does exactly that.

Look at the Soviet Union at the height of Stalinist oppression in the 1930s. Having the wrong book (not even necessarily a Western book but even a Soviet book that is no longer in good graces) could be a trip to the Gulag which for many was a death sentence.

A lot of it was driven by quotas that the police had to meet.