First, my apologies for replying in here. Second, I did notice some weird "speed movements" for the past days from the player Kintano, that is due to the huge packet loss he's experiencing + his ping(net) is not stable either. Though, what quite surprises me is how he's still able to pop players their head with just only one single click/shot with the lag he is facing. I can't tell whether this is some trick, skill or some third party modification who knows... , but I highly doubt that this is some skill or trick. Trust me, when you have an unstable internet you will most likely find players 'teleporting' from a certain position to another position and in this case 'lead aim' would be the solution to hit your target. Lately I've been a bit more active on EC and CTF and almost everytime when I get a chance to fight Kintano I'm experiencing an abnormal game behaviour of Kintano. This guy doesn't even seems to lead aim, he goes straight for your head even with his unstable ping , and a way for us to hit him is to aim to the right or to the left of the player model on your screen, but still before you're going to aim and press your left mouse button / release sprint button + holding your left mouse button you will find your head popped, and the weird part is that the sync doesn't even play out on your screen at the the time he hit you(it's so fast, almost like some sort of speed mofication), all you get to see is his player model trying to aim (but in reality) he's at some other position and he shot you while ago, in other words the player(kintanto) model you see on your screen is some kind of clone. Though, I'm not 100% sure if this is how the sync is supposed to work, but is the first time I'm experiencing something like this, and it isn't normal.
On edit : Speaking of the video evidence shadow.jack posted here, I don't really see any speed related modicification, for me it's pure crouch-glitching + packet loss.