Out of curiosity, what IS your definition of art?
I'll play. "Art" is determined only by the buyer. For me, photography is not art. Motion pictures are not art. Some paintings are, some sculpture is.
Like the poster up thread who saw the paint can and brush and thought it was a display (and these days something like that could be) the best example of 'modern' art I ever saw happened by accident. A pepsi can had fallen into the waterfall between the east and west buildings of the national gallery in DC and ended up standing up against the wall on one of the falls. It looked cool. In fact it looked better than any of the 'modern' works in the gallery.
Now some people may pay millions for photos or some paintings. I look at the item they are buying and think they are insane. But it's their money.
I agree with much of what you said. Regarding the question: Is a photograph or a movie art? I have no idea. I lost interest in the question a long time ago; what matters to me are more basic things, like how much do I get out of it, is it a wellspring or does it dry up after a number of viewings? Do I come back to it or not? If someone asks me whether a great photograph is art, I'd say, "Beats me...but it IS a DAMNED good photograph."