Dansa Serpentina (1900) [x]
Fun fact: there are actually hundreds of these kinds of videos. Often called Serptine/Butterfly/Annabelle Dances, they are some of the earliest things filmed. They give a modern viewer insight into just how groundbreaking it was to view things moving not in reality. Further, the colors you see are hand painted. Contrary to popular belief, most silent films (about 90%) were premiered in color with either tinting or hand painting.