Why sensor plane moves right when focusing far?
In this setup, the sensor plane moves right when we focus close and left when we focus far. (I think it's more clear which is which if you watch the webcast towards the end of this animation.)
Why aren't the rays that go perpendicularly through the center of the lens straight? Also, I might be wrong, but the parallel rays coming in from the left represent distant objects and the slanted rays represent closer objects. Based on the colour of these 'closer' and 'distant' rays, the 'closer' rays seem to converge more when the sensor plane moves right, and the 'distant' rays seem to converge more when we move the sensor plane left.