Break the indicated high score in an action level to unlock the corresponding 
bonus:

Airship Concept Video: Thorn's Airship, 2,000,000 points 
Alternate costume for 40 Below: Thorn's Airship, 1,500,000 points 
Alternate costume for Ash: Water Temple, 1,000,000 points 
Alternate costume for Chilla: Snow Temple, 2,000,000 points 
Alternate costume for Deep Blue: Snow Temple, 1,000,000 points 
Alternate costume for Flex: Thorn's Pass, 4,000,000 points 
Alternate costume for Kameo: Forgotten Forest, 500,000 points 
Alternate costume for Kameo: Thorn's Castle, 100,000 points 
Alternate costume for Kameo: Thorn's Pass, 2,500,000 points 
Alternate costume for Major Ruin: Water Temple, 2,000,000 points 
Alternate costume for Pummel Weed: Forgotten Forest, 400,000 points 
Alternate costume for Rubble: Forgotten Forest, 1,200,000 points 
Alternate costume for Snare: Cumulative game score of 15,000,000 points 
Alternate costume for Thermite: Cumulative game score of 24,000,000 points 
Animatic Videos: Thorn's Pass, 4,500,000 points 
Animatic Videos 2: Cumulative game score of 18,000,000 points 
Animation Video: Forgotten Forest, 200,000 points 
Boss Fights: Water Temple, 2,500,000 points 
Character Model Video: Snow Temple, 2,500,000 points 
Cheat Set 1: Thorn's Castle, 2,500,000 points 
Cheat Set 2: Forgotten Forest, 2,000,000 points 
Cheat Set 3: Water Temple, 3,000,000 points 
Cheat Set 4: Snow Temple, 3,000,000 points 
Cheat Set 5: Thorn's Pass, 5,000,000 points 
Cheat Set 6: Thorn's Airship, 3,000,000 points 
Concept Art Set 1: Cumulative game score of 9,000,000 points 
Concept Video: Thorn's Castle, 1,500,000 points 
Concept Art Set 2: Cumulative game score of 12,000,000 points 
Cutscene Player: Forgotten Forest, 1,600,000 points 
Cutscene Videos: Water Temple, 1,500,000 points 
Deleted Cutscenes Video: Cumulative game score of 21,000,000 points 
Deleted Moves Movie: Thorn's Pass, 3,000,000 points 
Deleted Scenes Videos: Thorn's Airship, 1,000,000 points 
Early Footage Video: Thorn's Airship, 500,000 points 
End Concept Video: Thorn's Airship, 2,500,000 points 
Evolution of the Characters Video: Snow Temple, 500,000 points 
Evolution Videos: Thorn's Pass, 3,500,000 points 
Making Backgrounds Video: Thorn's Castle, 500,000 points 
Music Player: Snow Temple, 1,500,000 points 
Test Cutscene: Thorn's Castle, 2,000,000 points 
Troll Song: Thorn's Castle, 1,000,000 points 
Wotnot Book Video: Forgotten Forest, 800,000 points