Since no one has commented, I will: Great video! Very nice viz for right off the beach. Was this in Pensacola Beach? I thought these rock "discs" were on pilings far enough off the bottom so they would not be covered by sand. From what I see in your video, the rock discs are close to the bottom. Does this mean than sand has already filled in most of the pilings? A little more sand deposition from a tropical storm and the discs will be covered; not good.
By the way, I just came across some photos of a similar reef-making project in Navarre Beach:
Photo : Northwest Florida Daily News
This project has been planned for years, and it is finally happening.