honestly as someone how has seen a lot of gross stuff on the internet i am not creeped out by it in any way. but i give it a quick break down in some of the ways it uses to scare someone.
i see the video uses some elements of Trypophobia, Stomaphobia, and maybe a little Dentophobia.
Trypophobia refers to the fear of holes. Stomaphobia refers to the fear of mouths. and Dentophobia refers to the fear of teeth. the videos also has some random fast changes and flickers of imagery and/or music. those are some things in the video i can see freaking out someone.