Hi,
I watched the demo, clean.
What prefire on short are you talking about? The ones in the last round? It was obvious that there were at least 2 T's on short + he started shooting at them right after he saw bullets hit the wall from his teamm8. Thats a pretty normall reaction.
As for the smoke thing, no idea.
My conclusion --> definitely NO wallhack, not sure about the smoke.
greetz,
Legion