Does not the video evidence make that possible?
The video evidence is consistent with a number of possibilities, especially for events that occur after the video ends.
You've been speculating that Husain was 'detained' after the video ends in a way Franco was not. The boys could have both been there until a parent came for them, or maybe one was let go and not the other, or maybe both were let go quickly.
I am not arguing for or against any particular scenario I am trying to find out what actually happened.