“From 1895 to the early 1950s, all commercially available 35mm film, stills, negatives and even X-rays were made out of cellulose nitrate: a fragile, combustible, unstable, highly-flammable substance that was also used in explosives.” But “[a]ccording to the eminent curators at the British Film Institute (BFI), cellulose nitrate film is the most vivid film stock ever created.”