Go to Special Features, then hit Downloads. In the next menu, click on Specifications. Highlight Special Features on that page and press Up. the "A | S" on the coffee mug will be highlighted and if you click it you'll get a 1-minute clip about Robert Crumb.
Extra Clip 2
In Special Features, either highlight Play Movie and press Right, or highlight Main Menu and press Left. This will highlight the speaker and if you click on that you'll get a 1-minute clip about the Genuine Nerd Toby Radloff.
Production Credits
Go to Special Features and either highlight "HBO Films" and press Down, or highlight "Play Movie" and press Up. This will highlight an icon. Press Enter for the DVD production credits.