Recently, various robots capable of having a video chat with distant people have become commercially available. This paper shows that movement of these robots enhances distant people's presence that the robot operator feels. We conducted an experiment to compare the degrees of social telepresence produced by fixed, rotatable, movable, and automatically moving cameras. In this experiment we found that forward-backward movement of the camera significantly contributed to social telepresence, while rotation did not. We also found that this effect disappeared when the camera moved automatically. We propose the user-controllable movement of cameras as a fundamental function for video-based communication systems.