compression?
I think he means DVDs with Dolby 2.0 and DTS 5.1. and no Dolby 5.1, which are pretty rare, in comparison with those with Dolby 2.0, 5.1 and DTS soundtracks. I was never sure if the video/sound needed to be compressed more in order to fit a movie DVD using all 3 of DD 2.0, 5.1...