Complex sentence: The Prank calls were mostly incoming calls where a video camera was trained on the reciving phone line and the Jerky boys would prank the person answering the phone from offscreen and record the subjects responses.
Split into simpler sentences: The Prank calls were mostly incoming calls where a video camera was trained on the reciving phone line. The Jerky boys would then prank the person answering the phone from offscreen and record the subjects responses.