Long story short, server side hit detection.
I split that last shot into a few frames below. The first frame is luxxiz's shot. The second frame is IJ's shot, slightly to the left of luxxiz. Three possible explanations here:
1) Assuming this is demo playback, luxxiz's position as played back via the demo recorder wasn't 100% accurate. This is pretty common given that demo playback in UT sucks dick.
2) Luxxiz's position as seen from IJ's perspective was not perfectly in sync with the server, so when the shot was fired and received on the server, the server "went back in time" according to IJ's ping and luxxiz's hitbox (as "remembered" by the server's time-position lists) was actually further to the left than what IJ saw. As for frames 3 and 4, you see luxxiz move back to the right in the amount of time it would take for the server to confirm the hit registration.
In the latest versions, I have actually added some stuff that should make positions more accurate but there's really only so much I can do.
3) IJ is cheating again.