The rolling shutter effect is an artifact in digital still photography and video that originates in the fact that a frame is displayed "at once", but recorded by progressively scanning the sensor. That means in a typical video frame taken by a digital camera the bottom parts show the world at a later time than the top parts. This becomes apparent when objects in the scene move fast in relation to the scanning rate of the camera.
A slower version of the effect can be observed when using a flat-bed scanner or photocopier: If the original or object on the glass is moved while it is being imaged very similar artifacts can be seen.
The rolling shutter effect has gotten a lot of coverage lately with more and more digital video being produced.
Matt Parkers video on the subject has reminded me of an experimental film I watched a very long time ago, when video was still analog and only TV-people had the equipment to record it. The film was of a set stage with people slowly moving about it and it was manipulated to show radically different times in different parts of the frame.
Unfortunately that is all I remember about it, and thus could not find any mention of it on the net, if you happen to know something about it, please let me know.
It occured to me that today an effect like this should be very easy to produce using digital video as input. So I wrote a little Python program to do it.
timewarp.py takes one video and produced a timewarped version of it by delaying the bottom row for a given number of frames beyond the top row. The code uses numpy and scikit-video and is bordering on trivial