The demo doesn't show anything aside from good use of sound, leading to pre-firing.
On a map like that, it's too easy to hear when people turn the corner. Figured I'd post the reasoning behind my "tee-hee".
I'm not saying that he/she does or doesn't hack, as I haven't played with her/him enough, but I don't see how the demo proves anything except the use of sound with headphones.
Not to mention, he/she is a baddie.