Yup that's a wall. Most of it could have been callouts or he could be using the map via the pop up if you bind it to a key on hand (that's what I used to do with my 7 key on my naga.) the shots could have just been skill because people do put a lot of time into the game and if they used their gun enough they know the general recoil. The delay behind the players when he shoots is just a known issue with the spectate because God forbid dice fix that to make admin work easier. The dead giveaway was that peek on A really. No shots were fired but he was already training the players head before he even rounded the corner.
I don't kid around when it comes to admin work. I would bounce out of games at times to spectate players back when I did it and found that issue. Unfortunately it still does happen
I have more doubts now about whether he was actually hacking or not. That pre aim at A was a little funky, but I've managed some pre aims that would look similarly suspicious on maps that I knew well. Maybe should unban the guy? Doubt we'll ever see him again, but I would hate to ban a legit, just talented, player.
There is a difference between a lucky peek aim and a definite hack. Seeing as he literally locked the head before rounding the corner and held it while rounding it is one of the most obvious giveaways. Take that in conjunction with the possibility of callouts to give those other near instant discoveries of locations but no evidence, we are in a pinch but I feel it is leaning more towards the hacker side. My judgement would be a ban and if he would like he may dispute it. If he is clean and it was a mistake, he will dispute or we will just lose one player that we have never seen before so I doubt it will have any real negative impact.