Heartbreaking video shows a little boy named Corey running as fast as he could on a treadmill. His father, Christopher Gregor, allegedly thought he was fat and prosecutors say forced him to lose weight by running on the treadmill. The video played for the jury shows him unable to keep up with the treadmill's pace and falling down. The 6-year-old boy died 12 days later. The autopsy says there was evidence of "chronic abuse." However, Gregor's defense team denies that and claims Corey died of natural causes from complications of pneumonia.