Screen Fit is a ZOOM function which zooms the picture in to eliminate the black bars at the top and bottom, BUT chops off the sides of the picture AND does NOT change the look of the picture it just zooms in. Not like traditional ZOOM function which simply zooms in without regard to the actual picture image and the black bars.
You have to do this every time you watch a movie that needs this special zoom function. And every time you check something which watching the movie you'll have to redo the Screen Fit.
Well, in my experience, if the DVD is 4:3 or Letter Box, it always stretches it to fit your screen. Which is annoying. Thankfully, you can switch this off by changing it's settings. From the player's Home screen go to [Setup] > [Video] > [HDMI Setup] > [Wide Screen] and then select [4:3 Pillar Box]. That way it will always display DVDs in their correct aspect ratio whether it's 4:3 or 16:9. Then you can always use the Fit Picture button to zoom or stretch to fit your 4:3 DVDs when you want.