You can query Apple official website's description of hotkeys and find the corresponding shortcut keys. Similar to most hotkey operations in Windows, almost all hotkey operations in OSX revolve around commands. Better yet, unlike some hotkeys that may be customized by various softwares under Windows, all softwares under OSX use the same set of hotkey definitions, such as entering/exiting full-screen mode, which must be Command+F. No matter what player, software or game provides full-screen function, it must be this.