Successfully complete one of the following tasks to unlock the corresponding bonus content for that level:

Allies and Bosses Art: Successfully complete the Curse Of The West level on the Shootist difficulty setting.
Attract Mode Movie: Successfully complete the Dead Light Prism level with at least 80 kills.
Cowboy Animatic: Successfully complete the Torture Maze level with at least 30 melee kills.
Darkwatch Archives: Successfully complete all Gunslinger levels on the Deadeye difficulty setting.
Enemies 1: Successfully complete the Boneyard level with at least 65% accuracy.
Enemies 2: Successfully complete the Showdown level with at least 20 melee kills.
Environments 1: Successfully complete the Darkwatch Outpost level with no deaths.
Environments 2: Successfully complete the Invasion level on the Deadeye difficulty setting.
Environments 3: Successfully complete the Curse Of The West level in 10 minutes or less.
Evolution of Jericho: Successfully complete the single player campaign on any difficulty setting.
Highmoon Trailer: Successfully complete the Rescue level in 15 minutes or less.
Rescue Intro Movie: Successfully complete the Hangtown level with at least 20 headshots.
Showdown Animatic: Successfully complete The Right Train level on the Shootist difficulty setting.
Vehicles: Successfully complete the Deadfall level with at least 20 headshots.
Weapons: Successfully complete the Morning After level with at least 70% accuracy.
Wrong Train Animatic: Successfully complete The Wrong Train level with at least 65% accuracy.