Hey, it would be no real, cause when sby shot you down, you are only
crytically wounded, not dead. You are able to speak through your helmet mounted radio, and even shout for medic. But the real would be, if your camera remain inside the soldier, and watch the sky only. So a wounded lying people won't recon the enemy as a ghost.
And anouther thing: injure the squad leader (usually giong 1st) then nade the all squad defending and medicig him(probably others throw smoke, and you still have the nade aimed). Or aim near shouting woundeds, and you will catch a medic. It's sometimes easy to cut down them even with the reviewed ppl by knife.

Or on enemy territory, palace c4 or claymore onto the woundeds(it sometimes hide it). The only bad thing, that there are not enough medic.

So at all, you don't have to kill them.
And about the headshot: it depends on that what angle the bulet hit the helmet from, cause military helmets have perfect ballistic propertyes, in compense of the bad penetrability. But it should be depend on the + % damageyou get. For example, if you get 300% damage (+200%), then you will not be revieved.
With other words, we should make a diference among the cases, if somebody's corpse can be found easyest way with a metal detector, and if somebody have been headshoted at the helmet from a proning position, while he is standing.(fx. behind a tall cover, there is a high probability for this)
About the mute: ppl will use then normal teamspeak in the background, like someones are still doing. The easyest way, if you see, what you have to.
Black screen: at least a tunel plz., with a bright light at the end.
