Never-before-seen Chaplin film

My friend Dominique Dugros sent me these wonderful screen shots from a previously unknown (at least to me, and probably to most of you) short film that might possibly be a precursor to the 1918 never-released film How To Make Movies(or perhaps a remake or rehearsal of some sort). The film was part of a French documentary called La Naissance de Charlotby Serge Bromberg that came out in 2013. I don't recognize the man playing the butler and the film was shot on a set which doesn't look familiar to me either, so perhaps it was built specifically for this film. I also wonder if this could have been made during the Mutual period. Perhaps Charlie had the idea for it then and went back to it later. But my biggest question is: Why have we not seen this before?