The "You Will Believe" bonus DVD (disc 13) isn't the only DVD in the Ultimate Collector's Edition only available as part of the 14-disc set. Disc 14 contains Bryan Singer's Video Journals, 29 chapters comprising the video production diaries (or video blogs) detailing the making of "Superman Returns". Most of the video blogs have been available previously online and as part of the Best Buy exclusive two-disc edition of "Look, Up in the Sky! The Amazing Story of Superman". However, disc 14 includes two previously unreleased video journals - "Outre" (chapter 28) and "KR 83.80" (chapter 29).
Chapter 28 is actually pretty funny. It's set up as a sequel to the blog where Singer flew to New Zealand to direct a scene from Peter Jackson's "King Kong". Like that blog, it's intended to be a joke - this time about Singer being fired off "Superman Returns". Singer decided not to release this blog during the production of the movie after he realized how many fans took the blog seriously where he supposedly worked on "King Kong".
Chapter 29 starts out funny with Kal Penn studying the differences between the actual Earth element Krypton and Kryptonite, the radioactive remains of Superman's home world. Penn has more lines in this video journal than he had in the whole movie - even including the line he gets in the deleted scenes. Unfortunately for Penn, his most vocal work on the video journals ended up in the same place as his most vocal work on "Superman Returns".
One final note: If you have the Best Buy version of "Look, Up in the Sky!", you unfortunately do not have all the video journals that were released online. The disc of video journals included in the Best Buy set only included 12 chapters out of the 27 previously released chapters (those 12 chapters were 4, 5, 6, 10, 11, 14-18, 20, and 23 for anyone wondering).