Hit the Nail on the head there pal B)
If killcam was to be recorded through demo/video, the server would become under a large amount of stress due to recording saving and replaying multiple times at the same time. So It saves what goes on through a text file (or so i believe in code) Now depending if your on a server thats the worlds olympics lagothon then these kills cams, quite obviously, will lie, which makes accusing hacking through killcam a very weak case in my opinion. Cos the killcam is only for a matter of seconds and isn't worth having on :) Thats why If I see demos where people show a killcam scene in it and say "theres no way he could have seen me!!" WRONG! there could have been a part where he saw you 10 seconds ago, you just didnt know :)
But yeah most of the problem probably was lag, maybe because the server you was in is over a 1000 miles away from where you live :) B)
Tell me, did you win or lose? :P