Comment by _joel

You have to align your face in certain ways, a random video you found on the internet won't work.

If you don't match your face to the markers overlaid on the screen in a certain way, to gather heuristics about your eye distance, nose etc, then it won't work. Impossible to do with a 2d object you're holding. So yea, it does matter.

There's a literal industry that's popped up to make face identitifaction from your smartphone a thing. You might want to research and catch up on the way they work.