Do you know about The Dialogue series of interviews with screenwriters? Not exactly featurettes, although there are often film clips used in the interviews.
I have a few The Dialogue DVDs. They're good for me because they have emphasized how difficult it is for a sucessful and proven writer to create a screenplay each time they have a go at it. All the problems I have had and still have, they too have had, and still have, and will continue to have. I learned to suck it up and keep moving forward, because this is tough territory -- so get use to it kid!