The bonus features on the I Know That Voice (IKTV) CD includes 16 additional interviews, 3 deleted scenes, the IKTV panel from the 2013 San Diego Comic-Con (SDCC), and commentary with John DiMaggio, Lawrence Shapiro, and Tommy Reid.
I started to watch the IKTV SDCC panel but stopped when I found out that it has some mild profanity. The commentary is most likely is for the documentary itself. The three deleted scenes are entitled "Getting Started", John DiMaggio: "The Meryl Streep of Voice Acting", and Chris Rock Animation (Part 2). The third one I really didn't care much for, but the other two were interesting. In my opinion, the highlight of the bonus features is the additional interviews. Five of them are voice acting tips and advice. It's perfect for anyone who plans to become a voice actor/actress. Nine are more or less reminisces and two are just... humorous.
You're probably wondering, "Who did the additional interviews?" Well, they are: Andrea Romano ("My First Time..."), Hank Azaria ("Creating Comic Book Guy"), James Arnold Taylor ("Maintaining Your Voice"), Dee Bradley Baker ("Stealing the Show"; "All the World's a Stage" (Full Monologue)), Billy West ("Origins of Zapp Branningan"), Nancy Cartwright ("Flapping the Unflappable"), Noel Blanc ("Bugs Bunny to the Rescue"), Jim Cummings ("Booth Etiquette"), Matt Groening ("Advice on Breaking in the Business"), June Foray ("Witch in a Phone Booth"), Kath Soucie ("Developing a Character"), Tara Strong ("Getting into Voice Over"), Seth Green ("Working with the Pros"), the late Stan Freberg ("Walt Disney Directing"), and Tom Kenny ("Timeless Talent"). Which of the 16 interviews are my personal favorites? I'll have to say Dee's "Stealing the Show", Noel's "Bugs Bunny to the Rescue", and Kath's "Developing a Character". Also, be on the lookout for a Perry plush in the "All the World's a Stage" full monologue (Hint: It's in the background).
I'll watch the actual documentary some other time, and might end up doing a review of it.