For the first one, go to Special Features and either highlight "HBO Films" and press down, or highlight "Play Movie" and press up. this'll highlight something in the yellow square (i couldn't figure out what it was). if you press that, you'll get the DVD credits.
the next one is better.. still in Special Features, either highlight "Play Movie" and press right, or highlight "Main Menu" and press left. this'll highlight the speaker and if you click on that you'll get a 1-minute clip about the Genuine Nerd Toby Radloff.
This one i found completely by accident. i was in the Languages menu and i was doing something else so it was just chugging along there with some dialogue.. after a minute or so a record player appears at the bottom. when it does, highlight it by pressing left from "Main Menu". clicking on it will give you a 1-minute clip about one of the special effects in the film.
If you just keep the Special Features menu open and listen you'll get to hear this dialogue between the fast food order guy and Toby Radloff (or Judah Friedlander playing him more likely).
Go to Special Features, then hit Downloads. in the next menu, click on Specifications. highlight Special Features in that page and hit 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.