Probably because video isn't terribly useful in determining what happened. Plane came in too low, tail struck the seawall. Assuming that is actually what happen

Probably because video isn't terribly useful in determining what happened. Plane came in too low, tail struck the seawall. Assuming that is actually what happened, this was clear as soon as the news helicopters were on site. All video would contribute (assuming that it doesn't exist as just isn't released as is suggested) is entertainment to the public. The interesting question to answer isn't the exact mechanics of the crash, but why the plane came in too low. All the video footage in the world is not going to answer the why - the flight data and cockpit voice recorders might, on the other hand.