The dialog is always in the center channel. The latter really helps to heighten the emotional scenes. The sound effects seem to mostly be in the center, and every once in a while in the surrounds. I took the DVD into the local Circuit City as a test disc when I was shopping for a new surround amplifier. Most of the sound and vocals come from the front left and right speakers, and hardly any from the center.
Some sound comes from the rears.
Since the center is hardly used, it sounds as if you are listening to the music videos on a stereo system in a really good sound room. Since the songs were originally in stereo when they were first released, this could be considered good because it's not a drastic audio remix. On the other hand, some people might think that the mix is bad and that the folks at Sony didn't want to spend much time or money to make a good 5.1 channel mix. As of right now, although I haven't heard many music DVDs, my opinion is former. More to come later on my other favorite audio mixes.