See the top comment from m4a1 mk3 about this shot lol.
I forgot about this video, Still i find that first wallbang hard to trust but saying that i've seen it done again by different players.
So I think this is legit just didn't know that spot at all.
I've tried it a few times never worked but i forgot about it "will go back to trying it"
p.s. I can talk for myself