When it comes to DVDs, I seldom pay much attention the extras.
Forget the shorts. Forget the cartoons.
I want to see the movie. Period.
I will check out alternate endings and an occasional deleted scene, but unless there is a specific scene that is of interest, I almost never listen to the audio commentaries.
90% of the "Behind the Scenes" documentaries on current movies are self-congradulatory and, frankly, dull. I hardly ever watch them for more than a few minutes, if at all.
I do enjoy the short retrospective featurettes that often accompany classic films, particularly when some of the original actors or other participants are interviewed.
What I enjoy the most are the feature-length documentaries, often orginally made as stand-alone TV specials, that are incorporated into some of the "Collector's Editions" Two examples: "The Making of GONE WITH THE WIND" and the documentary on Budd Boetticher that is included in the recent 5-disc release from Sony.
Also, not sure if it was made strictly for the set or for TV broadcast, but the documentry that is included in MURNAU, BORZAGE AND FOX is also very good.