For some reason the video does not embed
If they killed 1 person from a family, they usually killed all the family members.
Pol Pot explains it: "To kill the grass, you must also remove the root".
And they killed 1 person out of 4 in all of Cambodia.
Genocide is part of communist tactics. They create no value and are parasites to wealth of a nation. As they bleed it dry they have to reduce population or else run out of resources