Better to find the movie with the actual 5.1 presentation rather than 2ch pcm (unless it was your Dish set top box that was only providing pcm 2.0). Not familiar with Dish settings in any case (with Directv you choose DD on or off, off giving only 2ch pcm and there's no option to make it easier for tv speakers), but doesn't the information about the movie indicate what specific audio it is providing?