1. A method for creating a composited video frame sequence, comprising: at a system including one or more processors and memory storing instructions for execution by the processor: comparing a current scene state with a previous scene state, wherein the current scene state includes a first plurality of objects having respective properties, and wherein the previous scene state includes a second plurality of objects having respective properties; detecting a difference between the respective properties of the first plurality of objects and the respective properties of the second plurality of objects; in accordance with the difference between the respective properties being detected, retrieving one or more pre-encoded first video fragments based on the detected difference, wherein each of the one or more pre-encoded first video fragments is a portion of a full frame of video; and compositing the video frame sequence, wherein the video frame sequence includes at least one of the one or more pre-encoded first video fragments.