Complex sentence: The popularity of the American Ninja Challenge has led G4 to produce a version of the series featuring American contestants called "American Ninja Warrior", which is produced by Pilgrim Films and Television, Inc. Auditions on G4's website ended on August 18,2009.
Split into simpler sentences: The popularity of the American Ninja Challenge has led G4 to produce a version of the series featuring American contestants called "American Ninja Warrior". The program is produced by Pilgrim Films and Television, Inc. Auditions on G4's website ended on August 18,2009.