Perhaps it has encoded black bars on the top and bottom. You can often get a sense for the size of the actual video image by resizing the window a bit and seeing when the video starts compressing vertically or horizontally respectively.
If this is the case, you could fix it by right-clicking and going to Window -> Crop Black Bars -> Video is within 2.35:1 or one of the other options, so that no video is being cut off, depending on what looks good.
If I measure out the black bars and the width of the video image, it comes out to an exact aspect ratio of 1.33:1, or 4:3, so that would make sense to be the case.
DVDs are always 4:3, but usually they are anamorphic, eg. the image is instructed to stretch to the proper aspect ratio. In this case, they seem to have gone with extra fat black bars instead of anamorphic video. Either a particularly badly mastered dvd, or a bad re-encode.