Well, we think that time "passes," flows past us, but what if it is we who move forward, from past to future, always discovering the new? It would be a little like reading a book, you see. The book is all there, all at once, between its covers. But if you want to read the story and understand it, you must begin with the first page, and go forward, always in order. So the universe would be a very great book, and we would be very small readers.
When you write a novel or paint a picture, you have the opportunity to approach it and back off, tear up pages, write, rewrite, paint over, and come back to it. In film, once you start shooting, you can't restart the clock, and you keep moving forward, and you don't look back, and you don't go back. And that is, of course, antithetical to the creative process. It's really hard to generate a comfortable creative flow under that kind of pressure.