It might sound so strange as to why someone would want to have one of their dual monitors set up vertically with the other one right next to it set up in the standard horizontal position, but let us explain why it is becoming so popular with video editors...
Take a professional video editing program such as Adobe Premiere Pro, for example, your most useful panels in the program is indeed the Timeline window where you would compile your video in, if your screen is far too small you will find yourself getting rather frustrated by having to scroll and zoom in and out unnecessarily often.
Furthermore, other windows such as your project bin are also cumbersome and small by default. But a lot of these panels take up a lot less space by being in a list video, but list views are far more efficient at space by being in a vertically orientated window and thus turning your display vertically and having a custom layout saved for your editing preference is key.
Take a look at the video below by the YouTube channel: Becki and Chris on The Dual Monitor Set Up You Didn't Know You Needed!