ralf563
It looks like the box uses a script which allows the user to be equiped with weapons randomly but by looking at the video clip you posted it looks like you have to actually have/own the weapons you want to be associated to the box model/script. The weapons shown in the video are from an official FPSC Model Pack.
My guess is that you will also have to change some things in the script for this to work OK.
Your best bet is to search for the original thread that this model was posted in and read through it for information regarding the way the box works.
All the best of luck.
EDIT - Here you go, check out the link below.
http://forum.thegamecreators.com/?m=forum_view&t=159353&b=21