My screen has a 16:10 aspect ratio, why isn it listed in the View ➙ Aspect Ratio menu?
The View ➙ Aspect Ratio menu is actually about the aspect ratio of the file you’re trying to play, not of your screen. Usually, streams will include information about their aspect ratio directly in the file. You would only use the menu item item to switch ratios if that data was wrong. If you want to remove black borders, you should use the “Zoom” menu items instead, in the View menu.