So glad I came across this thread because it's been a pet peeve of mine. Back when I was heavily into film photography you could always tell the amateurs because they took all their pictures in landscape mode, no matter how tall and narrow the subject was. But we never saw movies made in portrait mode by turning the camera sideways because you'd then have to turn the screen and projector sideways to watch them.
But nowadays all the great unwashed make vertical videos on their cellphones no matter what then subject. Clearly, they have no artistic sense, or even a clue. Last time I checked my eyes were side by side and I see everything in an oval approximately 16:9. In art and photography the golden ratio is 1:1.618, between 4:3 and 16:9. But smartphone addicts who mostly just communicate with other smartphone addicts see everything in a vertical aspect ratio on their screens. Even when amateur cellphone video clips are shown on TV, they fill the sides of the screen with a fuzzy zoomed image of the same instead of black and don't apologize for the vertical format. I guess it's because everyone now is a self styled videographer with their smartphone.
Another quirk that bugs me is those mirror image selfie videos. I'm sure it's easier to relate to a video while they are making if it looks like a mirror, but it sure looks dumb to others, especially when the subject is wearing clothing with some lettering or logo.