FOXNews.com has video of passengers walking down a rollercoaster from the top where it had come to a stop (FOXNews's lousy link that probably won't work well is here: ).
I did this twice in the 90’s, but there’s no video to prove it.
Both incidents occurred at Darien Lake Amusement Park.
Once, the outdoor, wooden, coaster — The Predator — stopped at the top of the first big hill. We walked down steep, narrow, wooden stairs.
The other time, the dark, indoor, coaster — then known as Nightmare at Phantom Cave — stopped on a curve near the top. That was interesting. After several minutes they turned on the lights: an indoor rollercoaster is not all that impressive with the lights on. Then we walked down again (I don’t recall the descent being as frightening as the other time).