I'll be honest its a very short demo but does exhibit wallhack like behaviour - in particular the double back with no preceeding nade or opposition spam and his chosen spam angle taken through the mid doors is aimed at centre mass, needing to pass through both door and the edge of short rail to reach the target - resulting in hits of only 3 or 4 damage as a double wallbang. Good players aim higher - single wallbang leading to headshots of 50-70 damage.
However as it's not blatant and is a very short demo I would suggest deeming this insufficient evidence on its own, but a player worthy of watching in future and thank you for taking the time to report this Ov3rdOo$e.