The story consists of a hypnotist using his powers to make a subject's clothes magically change again and again. Of course, to do this, the camera was turned on and off...allowing the actress to change her clothes and then the camera was restarted.
In the 1890s, moving pictures were in their infancy and many of the plots of these films were dull...such as watching babies eating porridge and people walking down the street. However, a few filmmakers were trying new techniques and experiments with the camera. Using stop-motion, Georges Méliès began using his training as a magician and putting it on camera--with all sorts of crazy stunts stunning the audiences of the day. And, as was so common back then, other filmmakers simply stole or 'borrowed' his work to make similar films. The most famous of these 'borrowers' was Segundo de Chomón....but in the case of "Chez le Magnétiseur" his work was being 'borrowed' by the famous director, Alice Guy...who made a ton of her own and more original films. Original, this one is not. But it's competently made and easy to watch.