With the development of network technologies, there is an increasing quantity of users participating in various social activities by using networks. To enrich lives, some users record, by using a recording device, a video in which they play a role, upload the recorded video to a network, wait for another user to record a video of a partner role, and synthesize a costarring video from the video of the self-played role and the video of the partner role.
However, in the conventional manner, a role in a video played by a user himself is recorded first, and a remaining role in the video is filled with a piece of still picture or an animation, waiting to be played by someone actively. The efficiency of costarring is greatly reduced when the waiting time is excessively long.