Just looked it up, it is a commentary by Paul Sammon. Knew it didn't sound right having a commentary by PKD, which would have been by far the most valuable bit of extra feature on any of those discs. You are right, he did die before the film was released. He was never a fan of his movies being adapted to film, but pretty much the only way he ever made any money was by selling rights to his stories to film companies. I seem to remember reading that he watch a rough cut of the film (or parts of the film) before he died, and was actually impressed by it.

For any BR fans who haven't read PKD's Do Androids Dream of Electric Sheep, I highly recommend you do so. It is quite a bit different from BR, but it is really cool to see where many of the ideas that appear in the film come from. It also adds a lot of light to the whole "Is Dekard a replicant?" issue. It was a very important aspect of the book's story, I like that they added at least a vague hint of that plot line to the film, even though its vagueness seems to piss a lot of people off, which is why Ridley Scott made it less vague by coming out and saying he is definitively a replicant, and why the unicorn was added, both of which pissed people off even more.