I don't know about the DVD in question, and have never experienced an anamorphic 4x3 DVD.
BUT: When ITV digital was still functioning, the Carlton Cinema channel always broadcast its signal in 16x9 (ie anamorphic) despite the fact that most of their output was 4x3. I recall other channels doing the same.
Imagine a day, sometime in the future, when:
all TVs are 16x9
all DVDs and TV broadcasts are 16x9 (even when the contents are 4x3).
What we lose: A small amount of horizontal definition.
What we gain: A complete absence of user confusion over aspect ratios, and every TV on display in Curry's showing a picture correctly. You only have to trawl these forums and others to see how many users still can't cope with 'anamorphic' as a concept.
I believe that such a day will come. It may take national adoption of HDTV for it to happen, but it will come.