SeaWorld Orlando resumed its popular killer whale shows over the weekend, kicking off with an emotional tribute to Dawn Brancheau, the trainer who was pulled into the water and drowned by a whale named Tilikum last week as horrified spectators watched. As Sea World officials try to figure out what went wrong, several theories are being suggested: Animal rights activists say cooping up whales makes them "neurotic" and unpredictable, while a former SeaWorld trainer says Brancheau put her ponytail too close to Tilikum's mouth, and he grabbed it thinking it was a toy. Watch Brancheau and Tilikum moments before the attack in this video shot by a tourist. Were there warning signs?