What is the first film ever filmed? When was it and who starred in it?

It's an 11-frame clip shot on June 19th, 1878 using twelve separate cameras (frame 12 was not used) to film a man riding a horse on Leland Stanford's (the founder of Stanford University) Palo Alto Stock Farm (the eventual site of Stanford University).

Not exactly the high-action, special effects-driven, Braveheart-style, Hollywood blockbusters that grace our cinema screens today, but pretty impressive considering no one ever, in the history of the entire world, had made a movie before.

The film shows how Adolphe Le Prince, Sarah Whitley, Joseph Whitley and Harriet Hartley run around in the yard and laugh. Furthermore, we see that Sarah runs backwards when she turns around and that the slip of her coat of Joseph blowing up while he is on the turn.