there must be a way of of opening it??? i have tried capturing the leader but as soon as i go to tie up the other guys the plane crashes into the building causing the enemies to attack!!!! i've tried shooting them all but that doesn't work either???? does it open when all enemies are dead?? pleeeease help???? : (
I don't think you can open it, it serves to demonstrate that if you don't plan an ambush properly and quickly eliminate enemies during certain parts of the game then they will lock down the supply crates and you will miss out on Money or Weapon parts.
Have you tried throwing a grenade and then having a friend trigger the cutscene? In chapter 7 (or was it 6?) I threw a grenade before the cutscene started. As the cutscene was playing the grenade went off and killed the soldiers before they got to the civilian, so I only had to kill the one that came from the other direction. I haven't tried that on the part you're at, but give it a try, it might work.
The weapon crate on chapter two (the part right before the building you are in separates right over your head) as far as I know, is unobtainable. The mercs lock it down during a cutscene. I don't even think you can make a mad dash for it, since the cutscene triggers when you pass over an invisible spot on the floor.