In theory the DD or DTS 5.1 audio on DVD video can be better than CD. In actuality it varies depending on many things -- acoustics during recording (esp relevant if a live concert), quality of masters, quality of mix, etc.
I have Eagles - Hell Freezes Over DVD. Audio and performances are very good, plus you have the video. However the audio on the DVD-A Hotel California is much better.
If you want the ultimate audio, there's nothing better than the best multichannel DVD-A and SACDs. Unfortunately there are just a few truly great ones. Hopefully more will be released in time.
A particularly good DVD video is The Who - The Kids Are All Right. The DD 5.1 soundtrack varies in quality, because some of the performances (hence recording equipment) are old. But overall it's a superb example of high quality video (it's widescreen), high quality audio, and superb performances. Some of the performances are the best I've seen by any band, ever.
