There are audio config's that manipulate sound to the point of being able to distinguish which directions sound comes from, it's technically cheating and not accepted in leagues for competitive play.
Otherwise about the demo, some times at points in that, sound does isn't always a factor because some of the times people are walking, especially RyaN coming through tunnels and the 3 guys running into B at first you don't hear anything, well I don't anyway but I don't spend bucket loads on audio equipment for high fidelity sound, not that I think it would make much difference because of the audio engine in CS.
I based it on what I saw, no I didn't start recording immediately, there was a point where Duffman was was at the top of steps in tunnels, while RyaN was lower tunnels not making sound and Duffman is looking down past the stops and I don't mean the usual camping spot there, literally at the top of the steps, contemplating whether to throw a nade or not and waiting, not moving before RyaN moves out to mid DD and then nading.
Both Duffman and Stox1 were arguing about the other cheating and I've seen it before, you know, like a mini-private war of words as it takes one to know one? Stox1 definately cheated and seeing as he had first hand experience knew what else there was to be seen.
These are my opinions and there you go !
P.S. RyaN and Liquid both wanted J.V banned aswell, they complained afterwards about why I didnt ban him, well they doing it for ages.