A:Answer You can only do so much. The TV is actually upconverting the blu ray, but it has so much more data to work with.
Check out this picture that i've attached, which explains how small the native DVD picture is....Now imagine that the TV has to stretch that to fit the 4k screen. obviously it will not look perfect.
DVDs are never going to look great. Especially on any 65 inch TV. DVDs may look decent on a 32 or 42, but they'll just be stretched on a 65.
I suggest buying a blu ray version of the movie or renting a blu ray from redbox or renting/buying the digital version of the movie in HD and it will look much better.
you have to remember DVDs are not HD, they are not going to look good on a TV no matter what you do