Systems and methods for moving objects in a video using keyframes. An object may be added to a video and then defined to move in the video, for example, based on the movement of another video object for which movement is known or determinable. As an example, a video editing interface may receive a new object added at a position on a first frame of a video and a command to associate movement of the added object with the movement of a video object, such as a person that is shown walking in the video. In response, keyframe positions for the added object may be determined for subsequent frames preserving the added object's position relative to the person. The use of those keyframes is optimized. For example, the keyframes may be analyzed to eliminate intermediate keyframes with values that can be interpolated from other keyframes.