Complex sentence: Brumby then showed Frank the film to incite him to call the police on Kinnear as Brumby was too cowardly to do so this incidentally set up Frank assume the risk that Brumby would not take against Kinnear.
Split into simpler sentences: Brumby then showed Frank the film to incite him to call the police on Kinnear as Brumby was too cowardly to do so this. This incidentally set up Frank to assume the risk that Brumby would not take against Kinnear.