This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / Bo Burnham
When Bo's left and right brains are separated in "Left Brain, Right Brain", there are a slew of eerie sound effects, and if you see it live you get to see Bo at his knees in great pain while lights flicker repeatedly, which doesn't help much.
Bo's left brain itself. It's a cold character who feels little emotion. This sort of changes by the end.
The "Repeat Stuff" video's slew of Satanic imagery. At first, it becomes sporadically included throughout the video, but near and at the end it just pulls out all the stops. Bo, playing a generic pop star of sorts, breaks into a house to meet one of his fans. It quickly goes south as he takes her pillow and proceeds to smother her, and if that wasn't bad enough, he rips out her heart and eats it.
Not quite as bad, but it's pretty disturbing how he sits on the little girls bed and stares at her until she wakes up.