Yeah, that helo water evac was interesting, and in darkness no less!
When an evacuation is needed, there is an emergency. In most emergencies, many (if not most) people will revert to herd behavior and watch for clues in the people around them as to what they need to do.
We talked about this in a thread a couple of months back. Herd behavior and diffusion of reposability.
http://forums.equipped.org/ubbthreads.php?ubb=showflat&Number=274142&Searchpage=1&Main=19219&Words=%22BBC+article+on+survival+%22&Search=true#Post274142
As for what to carry, keep it small, on your body (not hand carried) and preferably in the front. You can control what is on your front better than something protruding out from your back. That is why I like a good size fanny pack. It can be worn diagonally over one shoulder, sitting on your front torso. It can be maneuvered around to the back or side easily if necessary, and can carry the items that will not fit in a pocket.
There's also small crossbody pouches or large neck wallets. Something about the size of yesteryears point and shoot camera case or a passport wallet.