To echo something someone else touched upon, I feel cheated when a commentary is edited from on-camera interviews, especially when those interviews are elsewhere on the disc. Just went through that with Gale Ann-Hurd's comments on Aliens in the quad set.
Cast commentaries are hit and miss, too. Like the comment about the American Wedding commentary, it can be disheartening to find an actor or actress you admire doesn't seem to have much on the ball. Kirstin Dunst's commentary on Spider-Man was a letdown, and Geoffrey Rush & Keira Knightley have WAY too much fun being cheeky in their Pirates of the Carribbean track.
Plus, one finds the cast members repeating stories you've already heard from the filmmakers on other tracks, and worse, they're telling them second- or third-hand and screw up the details. This happens on the LOTR discs.
Then there's Arnold Schwarzenegger, who in past commentaries (Conan), has little to say other than "that's right" or "exactly" in response to a co-commentator's statement. Perhaps he was chastised about this, for in his T3 commentary he goes on and on and ON describing what you're seeing on the screen, and says the same thing three different ways, all in a row. Verhoven does this, too.
I agree that being prepared is the key. Not OVER-prepared, though. The commentaries by the "Ian Fleming Foundation" guy on the Bond discs are way too scholarly. He's reading his own pre-written essays that probably look great on the page but are ill-suited for "conversational" speech. I seem to recall the Criterion Seven Samurai LD commentary sounding this way. In both cases, the information itself is interesting but requires one to concentrate a bit more than one might prefer outside a classroom.
I agree it was fun, at times, listening to Terry Jones' "person watching the DVD" track on Meaning of Life, but "joke" tracks that run the entire length of the movie (like the "alien" track on Galaxy Quest) make be bemoan the wasted bits that could've been devoted to the movie proper.
Point taken about how an individual's skills at self-expression might favor one medium or another. For instance, I can put thoughts to paper quite well, but articulating them verbally is quite another matter.
Even "bad" commentaries have
something to offer, though. The only one I couldn't get through was the new restoration of Metropolis. When the writing title card appears in the opening credits, the German scholar on the commentary says:
"Fritz Lang and Thea von Harbou: different sex non-identical siamese twins, like their film."
I played that statement over and over in an attempt to understand but couldn't stop my brain from hurting.
I gave up on that one just a few minutes later.