The intelligent multimedia playback device 250 is playing (step 703) first multimedia content. It may be understood that the intelligent multimedia playback device 250 may have played the multimedia content before step 701, or may start to play the multimedia content after step 701. For example, the smart television 111 in FIG. 4A is playing a video file “Stepping Bravely”, and displays a frame 401 of the video file. It may be understood that the smart television 111 may have played “Stepping Bravely” before being in the same WLAN as the mobile phone 407, or may start to play “Stepping Bravely” after being in the same WLAN as the mobile phone 407.