Word Request – Term for Swiping Finger on Lips to Mimic a Crazy Person

snuffle - to ​breathe in ​quickly and ​repeatedly through the ​nose, usually because you are ​crying or because you have a ​cold

I can't stand your snuffling any longer.

snotty has more than one meaning- one of which is 'covered in snot'. It doesn't really describe the breathing in.

snuffler is not in the dictionary, but everybody would know what you mean if you said it about somebody that does it all the time.

He's a snuffler.

Such a person is called an extra (or background actor).

From Wikipedia:

A background actor or extra is a performer in a film, television show, stage, musical, opera or ballet production, who appears in a nonspeaking or nonsinging (silent) capacity, usually in the background (for example, in an audience or busy street scene). War films and epic films often employ background actors in large numbers: some films have featured hundreds or even thousands of paid background actors as cast members (hence the term "cast of thousands").