When bassist Jason Newsted left Metallica in 2001, the band was in a tough position in finding his replacement. The need for a bassist arose during the recording of their album St. Anger, which coincided with the filming of their documentary Some Kind of Monster.
For the duration of the recording period, producer Bob Rock played bass on the album and in several live shows at which Metallica performed during that time. Once the record was completed in early 2003, the band started to hold auditions for Newsted's permanent replacement. Bassists Pepper Keenan, Jeordie White, Scott Reeder, Eric Avery, Danny Lohner, and Chris Wyse—among others—auditioned for the role. After three months of auditions, Robert Trujillo, formerly of Suicidal Tendencies and Ozzy Osbourne's band, was chosen as the new bassist.
Here is the footage from Some Kind of Monster of the auditions that took place: