I play with Billy regularly and have spent a lot of time spectating him and I even had my suspicions at first, however, he's just a very good scout (and market gardener)

If you watch the demo, open console and type "demoui" a UI will pop up allowing you slow the speed down immensely. You can see he misses quite a few shots each time, shows no signs of locking onto targets, and doesn't appear to know when someone is behind a wall.

But I'm all for another admin looking at the demo.
 
I'm very familiar with demoui and demoui2. Just because EVERY shot isn't on point doesn't mean he isn't cheating. He did enough to arouse many players. I would have recorded longer but he left.
 
I was on the server when this was going on and he was on red team and all of blue was calling him out, he was all over the place and his shots were spot on, ..thats when code did the demo but yea it was more than just 1 or 2 players calling him out, and then when someone mentioned recording him, he left.