Now I'm creating example, and have some minor problem with it connecting seems with mimeType.. I've sent the letter to proper developer and update you after complete example.
Has this issue been fixed? Is there an example of .avi or .mpeg rendering? Its paint method and value parameter?
At that time, I could not render a video using a4j:mediaOutput. As the requirements of our project changed, I did not need to do that anymore...