In the demo you can see he's extremely laggy.
The first kill wasn't fishy at all, just normal very bad spray control.
The second kill was definitely fishy. The flick was unbelievable.
The reason for it being 'unbelievable' is because his crosshair placement is terrible, he aims at the ground by default which surely means he's not a very skilled player so that shot was just weird as hell.
The possibilities are-
The first shot was terrible because he might have configured aimbot to not have anything that disable recoils, and that's why the crosshair was just right on the enemy while shooting which caused a spray which he couldn't control because of the aimbot which locked on to the player
Or it could be because he was unskilled to know that he CAN actually control the spray.
Second shot was weird as hell, the flick was unbelievable and the spray was the same.
Reasons he could be cheating :- Aim placement is terrible but weird flickshot
Reasons he not be cheating :- SS is clean no signs of any third party UI's.
Spray control was bad.
glhf