Exposed film in a can is even more useless than unexposed film in a can unless their is artistic merit in the exposure. Artistic merit is a service and not a tangible good. I can expose film in a can by taking unexposed film and opening the can. Hollywood is mostly a service industry.
When artistic merit is captured on exposed film, it becomes direct labor involved in the manufacture of that film. It is not a "service" but a value-added activity.
Although this is the mechanism by which wealth is created, there is no guarantee that simply engaging in such activities will generate a profit when subjected to competition in a market economy.