Movie 5 (:19)

Script : The streetlamp turns on and off. Even though the wall is closer to the streetlamp than the ground, parts of the ground are lit first. To understand this, we must consider not only the distance of the surface to the streetlamp, but also the distance to the eye.
Now, a schematic world where we can track the path of individual photons. As light makes the trip between the lamp, the surface and the eye, the light which follows the shortest path will reach the eye first. As the direct route between lamp and eye is shorter and thus faster, we see the lamp turn on before anything else is lit. The route to the wall is longer, so it appears later.