Since its inception this yearly series of races, which culminates at Olympia, has raised hundreds of thousands of pounds for charity. This year the chosen charity is Great Ormond Street Hospital. Between 50 and 60 jockeys and ponies have travelled the length and breadth of the country during the season all hoping to be the lucky 10 who make it to the prestigious Olympia week.
Re the thrown rider, the announcer's comment seems to be "These young children - they do bounce, they do bounce."
http://www.olympiahorseshow.com/programme02/, via Metafilter.