Dave Doe writes:

This is frightening! It works exactly like it says, and is one major
reason people in cars can look right at you (when you're on a
motorcycle or bicycle)---AND NOT SEE YOU.

No, the two phenomena are totally unrelated.

The demonstration shows the fatigue of the visual system (notably the retina)
when presented with a constant, unchanging stimulus. However, this fatigue
never occurs in ordinary life, because nobody stares carefully at a single
spot without moving his eyes and without a change in the scene for thirty
seconds at a time. It certainly never occurs while driving or operating a
vehicle, and is hard to elicit under other than laboratory conditions.

The reason drivers do not seem to see motorcycles or bicycles is very
different. They actually _do_ see these things, but they unconsciously regard
them as not important to their own safety, so they ignore them. They notice
cars because collision with a car is potentially harmful, but not motorcycles
or especially not bicycles because these are not potential "threats." It's a
simple example of awareness being directed towards the things that are
perceived as important. It has no connection to the visual fatigue described
above at all.