Vertical videos work against the way our eyes are placed and were introduced only because they work on vertical screens. Sorta because if you ever watched some interesting videos shot with a cellphone then broadcast from the TV, the ones showing important stuff going on -that is, not food recipes or kittens- you immediately realize there's something missing, and that something is the context in which things are happening: the surrounding area. You may complain about the black bars added on the sides and you're technically right, I however complain about the lack of context because the lower part of the picture shows the ground and the upper part the sky or some buildings well above the action. Our eyes are arranged horizontally because we live in a 3D but mostly horizontal space: if you shoot a vertical video of a car accident you almost certainly get a great picture of the 3rd floor of a nearby building but chances are that you miss completely a vehicle or pedestrian on the left or right that could have triggered the accident. There's a valid reason why screens are more large than high, and forcing people to shoot and watch vertical videos goes against any common sense in the name of selling more and more cellphones, services and advertising.