What do the playback settings mean?

[Mody birdy]

"Other application fullscreen" is pretty self explanatory

"Other application maximized" I'm guessing means games that are running in borderless windowed?

"Other application focused" What does this setting mean?

[(笑)]

Maximized means when you maximize a window (minimize, maximize, and close) and focus means you are actively interacting with the application. Say you have your browser window and file explorer open side-by-side, the one you last clicked on is in-focus.