Disarming of reinforcements to Airport??? What a strange war.

Apparently, this is a video shows reinforcements going to the airport and getting disarmed at a DNR checkpoint.
Why didn’t they kill everyone at that checkpoint? Was this agreed upon in advance? Money changed hands?

Andriy’s comments: So, separatists pretend to keep the truce (because of TV journalists in the bus). They are checking Ukrainian convoy – if there is allowed amount of firearms, bullets, equipment, food etc
Russian officer wearing white uniform pretends that he is local man from Donetsk.

Ukrainian officer speaks: “Last time some of your men has stolen our cigarettes”