Look I get both sides here. But realistically Disc Golf is not a big $$$$ for the pro's. So if He asked to not have it filmed, I think that he has every right. It is a "Free Clinic" it's not a free video. Pony up some money to buy the video if you can't make the free one is all that he is saying. You watch Colbert, the daily show, you pay cable to watch it, but the guest wants you to guy buy their book. This is one better, you get a free lesson just by showing up, and then in turn if you want to get a professional done DVD or download, you have to buy it.
I also get the whole idea, well its a public park, they can't tell me what to do....yeah, you are correct, but the other option then is to move it to a store where you are charged for coming in, and then the "free portion" would be to move it to the park. This is a good thing for Dave to give as he passes through, and to honor a request in order for 60 people to get something for free seems pretty simple to me.
He could have gone to Smithville with it, and charged everyone for parking!
Seriously though this is a current top playing pro giving away his time to 60 people not asking for a dime, but only asking that no video be taken. If I was there, I would be thinking about my throwing style more than I would be worried about the video buttons at any rate as well. So give him the request, and be grateful that he stepped up and helped some of the local talent get excited, and better!
Then ask how to pre-register for the video, and if there is a discount for paying early!