I still rent Netflix DVDs primarily for the commentary tracks. Most common tracks are the Director with either a Producer or some Actors. Occasionally I will find one with the DP among the commentary.
So far, ones I have found that were very informative were:
Capote - Adam Kimmel (Lars and the Real Girl, Never let me Go)
Scott Pilgrim - Bill Pope (Matrix trilogy, Fur, MIB 3)
Tropic Thunder - John Toll (Braveheart, Iron Man 3) - He doesn't say much in this.
Not a DP, but I've been watching early Bogdanovich's work with Lazlo Kovacs (Targets, Paper Moon) Peter goes into great detail about how they worked together in planning the shots.
I am curious what DVDs you have found that have DP commentary tracks available? I'd love to rent them.