Many many early DVDs were simply Laserdisks copied over. I figured this out listening to the commentary on the Spaceballs DVD I rented from school. Mel Brooks made mention that he was making this commentary in 1994. So I assume this is the case here. I think Khan was released July 1997 on DVD so was among the first batch of them.
P.S. Brooks is a lousy commentator. Really boring. Matt Groening has excellent commentaries though.