Water clarity and amount of light penetration is another factor. I got an Aquaview DVR with a 1GB card and still learning how to use it better. Have a couple of programs to add in soundtracks, titles, etc but gotta play with it more. I did post one that I did at Gull. Water clarity was about 2-3' and I was fishing at 6' Set the Camera vertically so I could move around quicker and get setup.
http://www.youtube.com/watch?v=TDFMvepgdKg