There is a similar event in my neck of the woods next weekend. It happens on a main street (US-24) lined with crowds of onlookers. I'm sure that a drone could be flown responsibly and safely at these events, however not down at street level over crowds of people. My recommendation if you need to film one of these events as a hobbyist is to first ask permission of the organizers and fly above a building with the owner's permission. Stay away from people and certainly stay away from horses that may be familiar with crowds, but not with drones. If you're gonna do it as a pro, that's a whole different ball of wax.