Default Widescreen projection TV & the black bars

I went to Costco (huge US warehouse-style retailer with everything from electronics to tools to food to car stuff) yesterday just to pick up some groceries, and ended up with this:

The manual warns about leaving constant images on the screen, including dark bars from having normal TV centered and not in the expanded mode. Is this for real? Seems like black bars would be, by definition, a non-image, right? Scary warnings in the manual though. Anybody know how real they are?

The expanded mode is OK most of the time, just a little weird. It expands stuff that is off-center, so the effect is less noticeable, but sometimes you really see it. Really ruins your porn when the actresses off-center looks like a Jenny Craig "before" model.
I like my women like I like my scotch. 15 years old and mixed up with coke.