Most studios still release DVD's with 2ch DD and 5.1DD. Since 5.1 is automatically down-mixed to stereo it seems to me like it's a waste of space on the DVD. The DVD consortium requires that the 5.1, 6.1, etc tracks have to be down-mixable to 2 channels. I can't think of a logical reason why they keep releasing discs with 2 channels and wasting space that could be used to reduce compression on the video. Any ideas?