I think you have misunderstood it.
There are two types of DVD discs with audio.
1. DVD-V(ideo) with audio
2. DVD-A(audio) with of course audio, but can also hold video...
Type 1 is much more common than type 2 and type 1 is the type that any DVD player can play, also in multi-channel.
The Panasonic however, can also play the 2nd type but as you have noticed, only in 2-channel.