Here is the interview with the photographer with multiple runs of the video. He had gotten out of his car and taken shelter in the restaurant but left the camera which was pointed towards the bridge running. He was at the right place at the right time.
http://on.aol.com/video/severe-storm-winds-blow-train-cars-off-bridge-in-new-orleans-518791635
I am in awe of the wind. Impressive it could blow something like that over.