Hi Dean,
If you want to use a filter in green water I would go for the UR Pro GR filter - as it is specifically designed for such conditions (its the pinky one, rather than the orange one).
Alex
For your interest, here is the FAQ from the Magic Website about green water - which is about still rather than video photography:
Does the Magic work in Green Water?
The Magic Filter is designed for photography in brightly lit, tropical blue water. Filters work by subtraction of light, and green temperate waters are less suitable for filter photography because their is less available light to begin with, less light penetrates the water because it is usually rougher, less light penetrates to a certain depth because it is scattered by particles in the water, and because of this scattering the light that has reached this depth has actually passed through more water than at an equivalent depth in the tropics and therefore requires a stronger filter balance the spectum. Ambient light photography in green waters is usually best either as black and white or as very shallow water photography with filters.