Wait, for the video I think you're right. After taking a closer look, it looks like it says "Press A to Interact". Perhaps there's no more ammo boxes? That was the only thing I've seen that almost looking like one.
I can't remember if we've had a solid confirmation of this, but its pretty well assumed that they are gone since we haven't seen any and that there are suit upgrades to help with ammo now. Maybe Tony can say for sure.
Everything I've learned about life can be summed up into three words: It goes on -Robert Frost Wanting: Golden Sun Dark Dawn, Conduit 2, AC Brotherhood
Looks like a switch of some sort. Probably just activates something on the map, is all.
And I like that there aren't any ammo boxes...yet. It'll be harder to get kill streaks if you run out of ammo, and I think it would be cool to scourge around and find another weapon with more ammo to continue your kill streak.