Youtube is amazing.
I found a short film that was shot in 1903. Though the "storyline" isn't railroading, per se, it was filmed on the Lackawanna Railroad. If you'll watch the backgrounds, etc, you'll see glimpses of 1903 railroading.
For example, the first scene, watch the background as a freight rolls through at a good clip... with a brakeman standing on top of a car!
You'll also see a Camelback locomotive.
Well... here... see for yourself: