A video playing device capable of external connection to an application processor includes a remote controller and a processor. The remote controller includes a first button group having a plurality of buttons for use in operating the video playing device and a second button group having a plurality of buttons for use in operating a portable carrier. The processor processes an external video signals and portable carrier video signals from the portable carrier, sends the signals to a screen, and processes remote control signals corresponding to the first and second button groups. The processor sends to the portable carrier a plurality of signals according to the remote control signals of the second button group. A portion of the signals triggers the application processor of the portable carrier to execute a plurality of App accordingly.