The updated YouTube iOS app can use the entire screen of the smartphone Apple iPhone X
The aspect ratio of 19.5:9 characteristic of the screen of the smartphone Apple iPhone X, is not optimal for viewing videos, as the most common aspect ratio is 16:9. The result of the fields on the sides of the useful dimensions of the screen does not even reach five inches.
In the latest version of YouTube app for iOS the problem is solved in the most obvious way — the picture is increased enough to cover the whole screen width. It lost some of the image top and bottom, but that fee and non-standard aspect ratio screen. We will add that a little lost and on the sides, because the shape of the screen simple rectangle: one side is cut and the other rounded clipped corners.
However, if the option fields on the sides is preferable, you can use it — the program allows it.