From what I saw on this demo, I'd happily call it conclusive of a wallhack.

At around 7,000 tick, he circles around a corner, prefiring and aiming hard. He's constantly tracking players through walls as well. When the CT was escaping with hostages, he was tracking him through the wall. Right at the end, he lines up the AFK CT spawn kill (kill gets stolen, but the lineup is still there) and continues to line up CTs in the glass boxes on the side of CT spawn.

I'm gonna go to the Office server now, see if I can catch him in there. If not, then I am going to ban him. If any other admins check this demo and disagree, now would be the time to post. I think its conclusive enough for a ban though :\