Don't get too excited. It states: "The use of drones and remote controlled flying models is permitted only on the Flying Field in Richmond Park." A flying field is typically a small open area of a park. In fact, if you click on that map on that page and switch to satellite image, you will see those ponds are not part of the flying field, nor is most of the park. Probably best to ask at an information booth what the flying area limit is so you don't get a fine.
Actually, the field sign in that video states that flying is only allowed within a 250 ft radius of that notice so it appears this guy is flying well beyond the permitted area. You are also required to have $10,000 of liability insurance to fly there, according to the same sign.
The next step will be for the park to ban drones completely because of people like that guy.