Not a single film, but I would say the Up! series of documentaries by Michael Apted, as a whole, is the most inspiring I've seen. The ability to roughly trace fourteen lives, their personalities from childhood to adulthood, their idiosyncrasies, their thoughts and opinions, their dreams and disappointments, over the course of now almost 40 years, that's a real gift that only the movie camera can bring, so vividly. The early Lumiere/Edison silents are also very inspiring to me, for similar reasons. Seeing those always puts the invention of the motion picture camera into a cultural, social, and historical perspective for me, and makes me realize what an amazing thing it is that we can look back and see Gandhi, Hitler, Martin Luther King Jr, The Beatles, Elvis, Olivier, Chaplin, Marilyn Monroe, FDR, JFK, Nixon, Churchill etc. as they actually were and not have to construct imagined versions of them through photographs, writings, and paintings, and people hundreds of years from now will always be able to see and hear them preserved, along with all of our contemporary giants, milestones, catastrophes. Even the little things, people in the year 3000 will be able to see "Charlie Bit My Finger" and laugh at two little boys from 2007. I like to think about who and what we might have been able to see today if the movie camera had been invented 100, 500, 1000 years earlier, what more we'd be able to learn, and of course how they would have expressed themselves and responded to the world around them through filmed narratives. What kinds of movies would they have made? Where would movies be today? Of course, it also gets a little depressing when I think of some poor future anthropologist stumbling on an episode of Jersey Shore....