There is a psychological principle that Freud called “the uncanny.” The feeling of the uncanny is the sense of fear, horror, and revulsion that people feel toward things that look very near to being alive, but aren’t. This includes things like mannequins, statues, dolls, and even corpses. You have probably heard the term, “the uncanny valley” in relation to computer animations of human figures, as the revulsive feeling of the uncanny actually increases the closer a humanlike figure gets to looking real without actually being real.
The feeling of the uncanny also applies to doubles—from doppelgängers to staring too long at your own reflection. Your reflection is another thing that appears human, but isn’t. And, unlike mannequins, it’s getting really really close, but no cigar.
So if you jumped while viewing this viral video of a woman supposedly holding her cheek up to a mirror and displaying how her facial expressions and movements are not showing up in the reflection—the the uncanny has its hold on you.
It’s a fun video, if you like being spooked so bad you spill coffee on your lap at work, but it’s not real. Pro tip: check the angles. You can easily do this yourself with a hand-held mirror in front of the bathroom vanity or even in your own cellphone. Briefly: if a face was really being held at that angle against a mirror, the reflection would not be visible because the mirror would be perpendicular to us.
Clever edit, though.