The guy that was killed on the killcam was the guy he killed before he killed you. You can see where it says "YOU" before you come around the corner. You didn't watch the whole killcam. Not saying this game doesn't lag, just pointing out that you didn't watch the killcam long enough.
I also suffer from far too many wtf moments so decided to try your idea of using my phone as a hot spot....
If this is how the other half (ie the peeps with slow internet) get the game; I'm going to get rid of my fast package!
Have you tried it? If not don't jump to conclusions.
I decided to try it to see if it was BS (I expected to find that it was false), its not. Granted I used the highly unscientific method of personal perception. But having tried four games (1 on Ethernet, 1 on wifi, 1 on phone to wifi & 1 on phone to 4g) I can say there was a noticeable difference between the wired connection & all three wireless methods. Why? Who knows! But since my 4g provider is different to my ISP we can safely discard the "it's you net" & "It's the geolocation of your ip" arguments immediately.