Note that extras tied to specific episodes are reviewed with those episodes.
Interview with Joss Whedon & David Boreanaz—Joss Whedon explained how he planned to fight the cliché of the blonde girl who walks into the alley and gets killed. David Boreanaz gave some spoilers about his character that will be addressed in episodes through the end of season 2. Anyone who has seen the first two seasons would know everything that he says, and anyone who has not should experience the episodes rather than watch this interview. This interview is skippable.
Buffy Trailer—The trailer is quite amusing and does a good job in capturing the tone of the show. This extra is located with "Welcome to the Hellmouth."
Photo Gallery—A selection of 27 production stills. This is of mild interest.
Biographies—Provides biographies for Joss Whedon, Sarah Michelle Gellar, Alyson Hannigan, Anthony Stewart Head, Nicholas Brendon, David Boreanaz, and Charisma Carpenter and the characters that they played. Most character biographies contain spoilers for season 2 and Willow's and Cordelia's biographies contain spoilers for season 3.