Place it right after the bad decision in your edit, following a Dun Dun Dun sting and before a SpongeBob Fail sting, so the sequence builds from warning to reaction to payoff.
このサウンドについて
This 6.6-second clip catches Markiplier mid-reaction, repeating 'no, stop, what are you doing' in a rising, flustered voice as if he has just caught someone making a bad choice on screen. It feels panicked, exasperated and instantly funny, like a friend stepping in a second too late. The line comes from the YouTuber named in the upload.