There is at least a second where they carry on after killing you. Enough to see which direction they sprint off in anyway. I think it's still a valid tip so i'll leave it in. If someone is camping and pop out from behind something to kill you, you can see if they pop back behind or move on. You can use this to your advantage if your watching, or alternatively if you are the killer you could pretend to go back, put a claymore there, then move somewhere else.
Just messing around with the killcam to test this i found out something amazing that i never knew;
if you press start while watching the killcam you can see all the enemies as green arrows as if you are viewing their map. As they are their team mates it doesn't matter what perks they are running, they still show up!!! Apologies if everyone already knows this, but i found it amazing that something like this is possible. It's like a free UAV everytime you die