It is moving stereographs.
A stereograph pair moves, and it isn't movie film......
There is various system to a stereograph.
It is a stereo pair that is the simplest in a three-dimensional vision.
Set images for the left eye beside for right eye and to watch that "this is one image".
And this Stereoscopic free viewing is "Parallel freeviewing method"
and "Cross-eyed freeviewing method".
When there is distance of two pieces of photographs, both methods are no good.
Can't watch a big stereograph in Parallel freeviewing method.

Spring, 2000
Marichan of Marichan's camera world did splendid discovery!
That is an epoch-making method.
Synchronize movement of two pieces of photographs through two mask windows of the size
that can stereoscopic free viewing.
Till then,I wasn't able to find a good answer about "a way to watch stereographs on Internet".
I made it hastily with unfinished interface for other works.