film's usually don't have an "artists statement", yet you judge them. you do not know the artists intention. just your subjective opinion to the experience.
I usually know something about how the film was made, what the people involved have done before, how it might fit into certain career directions... I might read an interview and at least get some minor insights. It's not pure truth, of course, but it's better than nothing. Doesn't everyone do this after they see a movie? And doesn't it almost always add something meaningful to your deified "initial response?"
its like looking at a breathtaking painting - loving the painting for the text of the image and then finding out that hitler painted it and hating it for the context of the creator.
But it's so much easier to use external knowledge with paintings than the kind of sculpture and photography that Ghostboy is talking about. You can easily determine some things about technique, style, movements, etc. And still it's limited. Biographical and historical details, little bits of research, knowledge of where and how the piece fits in the artist's career... these are all meaningful, though certainly not instant.
But what if you don't get that chance? To use a personal example - if people knew how my most recent film was made, they'd probably like it more. But they don't, and I can't expect them to - and although the information is available to those who seek it out, I can't make it an integral part of the exhibition.
Well, their knowledge is still limited, isn't it? You may feel helpless, and it may be a sad thing, but it's true. Your knowledge of your own film is probably limited in some areas. "Why did I make that choice? What does it mean?" You may never know the answers, but the questions are probably worth asking.
But unless the viewer approaches a work with preconceived notions, then contextualization is up to the viewer, and based on examination and evaluation of the content.
What about contextualizing after the fact and revising your understanding? We do it plenty. It's not as if the initial reaction is set in stone, though it may be the most powerful impression because it's the first one.