system
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human
ELI5: How do ISIS terrorists make sure the people they are executing or beheading on Camera do not fight back or try to escape during filming?

So I have just seen a couple of videos filmed by the ISIS thugs in Libya. In these videos the victims are just lined up kneeling in front of a beach and brutally beheaded. The one thing I find curious about these videos is the sheer hopelessness and borderline emotionless reaction of the individuals being killed.

Is it absolute fear? Hopelessness and Helplessness? An acceptance of fate? Or is there something else in play. 
I know it’s not beyond those monsters to weaken their captives by making them go hungry and refusing them water, but still, is that really enough to make a person surrender his life without putting up a fight? I also know that most of the victim’s hands are tied from behind but they still have their legs free, yet there is no kicking and screaming, you don’t even see them shading a tear or act in any way you would reasonably expect from a person facing a brutal death.
And is it really asking too much bravery from those souls to expect one of them to say “You may take my life but Goddamn it I will ruin your money shot.”?

The spokesperson in these kinds of videos usually goes on an endless rant before commencing the execution process but you don’t see any of the victims reacting in any way during this whole time. Even when in the very last moment when they are thrown into the ground and horrifyingly dismembered there isn’t much reaction. How is this possible? 

Even if there is probably no chance of escaping from their ill fate, what do they really have to lose? Getting shot while trying to escape seems a much better way to go than getting your head chopped off. it strikes me as a bit unnatural for a person to just give up so completely without his reflexes kicking in in such a situation.

Edit: Thanks for all your responses I have now found a number of articles that support the claim most captives are forced to go through mock executions and drugged to make them unresponsive.
gpt
A soldier who was kidnapped in Iraq and held captive for 2 years did an AMA. He said that they would often do "mock executions" where they would run into your room in the middle of the night, put a sack over your head and take you outside where they would say things in arabic, then put a gun to your head, only to let you go back to your room. After 50 times, it won't scare you anymore, you think it's just another mock execution. It's really fucked up.