Everytime I walk into an A/V section of a store, inevitably there's a DVD playing on a new widescreen tv. My question is how come some movies, even though they're playing on a widescreen tv, still have the black bars at the top, and some DVDs fill the whole screen with no black bars. Both movies are the widescreen format, yet some have the bars, some don't. What's the deal with that? Is it the TV? The DVD? Where do you look to see what you're going to get?