Hi Woodelf
On a traditional shape TV screen, with a 4 to 3 aspect ratio, the viewer will see black bars across the top and bottom of the screen. On a widescreen TV, with a 16 to 9 aspect ratio, the image will fill the screen. (Indeed, for most modern TV sets, 'anamorphic widescreen' is exactly what is needed for the optimum picture).
I recognise that, because of your visual handicap, this link will be absolutely useless to you directly (as it relies upon pictures to provide an explanation) but I offer it to you anyway, in the hope that it will be helpful to your partner or whoever else might be buying DVDs in your house:
http://www.tvshowsondvd.com/n/3997