  We present a method for retiming people in an ordinary, natural video --
manipulating and editing the time in which different motions of individuals in
the video occur. We can temporally align different motions, change the speed of
certain actions (speeding up/slowing down, or entirely "freezing" people), or
"erase" selected people from the video altogether. We achieve these effects
computationally via a dedicated learning-based layered video representation,
where each frame in the video is decomposed into separate RGBA layers,
representing the appearance of different people in the video. A key property of
our model is that it not only disentangles the direct motions of each person in
the input video, but also correlates each person automatically with the scene
changes they generate -- e.g., shadows, reflections, and motion of loose
clothing. The layers can be individually retimed and recombined into a new
video, allowing us to achieve realistic, high-quality renderings of retiming
effects for real-world videos depicting complex actions and involving multiple
individuals, including dancing, trampoline jumping, or group running.
