These gridded fins were used many years ago in missile technology. This is the exact same configuration as the ones I remember but used on the rear for guidance and stability. I though they were innovative the first time I saw them. Looks like borrowed tech to me now, lol.
It is borrowed tech, and don't let the slowness of the rocket in the video clip confuse you. When these fins get used, the rocket will be coming down through the atmosphere almost as fast as a missle. They borrowed it because if it worls for a missle, it will work for them.