A day at the races ended tragically for a racehorse at Churchill Downs on Thursday. The five-year-old non-competing mare named Never Tell Lynda was talking toward the paddock when she fell and hit her head. The trainer says the horse was startled by the sound of a starting gate during a commercial playing on the new, 750-speaker video board, which is the world's largest. The track says it's investigating the incident and the issue of speaker volume.