USBs are a significant form of sharing information in North Korea. Many citizens have devices with USB ports and SD card slots. So for many years, North Korean defectors have organized efforts to smuggle outside info into North Korea on USB drives to counter Kim Jong-un’s constant propaganda. But these groups were buying memory devices at cost with limited resources. Flash Drives For Freedom is a campaign that travels the world inspiring people to donate their own memory drives. An initiative launched and managed by the Human Rights Foundation, Flash Drives for Freedom is significantly increasing the capacities of these North Korean defector groups.
Apparently the use of flash drives is due to the police shutting down power to a neighborhood and then doing raids. With a DVD player a disc would be stuck when the power is cut. So the police roll in and see you've been watching contraband and off to the dirt mines. With a flash drive you can remove it from the port and hide it even with the power out.
https://flashdrivesforfreedom.org/