Thanks Bubbletrubble! I can imagine the videotaping would be a great help! I only wish I had access to an underwater camera. I don't own one myself. Maybe one of these days I will! Seems like a really good way to evaluate what you're doing.
You don't need an underwater camera. You could put one inside a plexiglass box or something similar and have someone video it from the surface without it ever having to go under.