dud4 it's called warping and it's only caused by an unstable (cable) connection. I had the same for ~2 years and yes, it's much harder for your opponent to hit you...
well... i dont wanna blame anyone, but i saw a few times at some players who plays with 15-20 ping and his movement looks like laggy, u can see it really if ya slow down this demo.. this doesn't causing any problem to play with it, but for the oppent that is really sux , cuz it's fucking hard to aim vs player who got this.. dont wanna say it's a cheat, but too strange, maybe it can be some script what causing this.. dunno.... and that would be intresting if it's a lag or an all time pl , with a not moving 2x ping. about the railfrag at gl , what so special there?