I wish that the presentation of Star Wars series OnDemand would play it without the black bars, it looks strange on a 16x9 screen.
You have black bars on the top and bottom of your screen because the movie is being shown in its original aspect ratio (OAR). Most widescreen DVD movies are also presented in their OAR and thus tend to have different sized black bars on the top and bottom of widescreen HDTV sets.
I don't think any picture with black bars is true HD, I think if it has the bars it's 480p upconverted by broadcaster.
I have found many programs that don't have the black bars when played. They should be consistent, not off and on.