The film includes a sequence describing Melies' famous (but probably apocryphal) story of how he accidentally discovered stop-motion substitutions while filming at the Place de l'Opera in Paris. We see what looks like actual footage from the 1890s, but as far as I know, Melies' original film at the location is completely lost. Have they found it, or did they do a reconstruction and not credit it in the film?
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They included a title on every clip they showed from a Méliès film and not for films from others. I think it's safe to say that the Place de l'Opera footage is a reconstruction based on films made by others of the apocryphal story.
The facts that Méliès projected Edison films at his theatre before he made his own and that the Edison Company had already discovered "stop-motion substitutions" for the film "The Execution of Mary, Queen of Scots" (1895) really raises doubts over whether Méliès rediscovered this technique by accident. It at least alleviates the need for that.