D'oh! Now helmets are going to be mandatory for spectators too!
I agree, that was pretty reckless and stupid on the part of the racer. A pound or two doesn't seem like much until it is moving at your head at 25 mph. I wonder if the spectator was feeling any effects later on after the adrenaline wore off? I hope it was no worse than it sounds.
I once heard a story of a racer crashing himself while throwing a bottle away. He threw it across his body (such as with his right hand, to the left side), jerked the handlebars, and took himself out! Fortunately no one else was hurt in the process.