All screens larger than 32” are supplied as standard with USB connections built in. If you are displaying .mov or .mp4 content then this will display direct from your USB device when plugged into the screen. This display can sometimes be clunky, though. A Media Player allows your content in .mov, .mp4 or many other file types to be displayed and looped seamlessly so that you don’t have to keep returning to your screen to press play again when the content ends.
If you wish to display USB content on a screen or monitor smaller than 32” then you will require a Media Player with your chosen screen.