Curious what focal length/field of view people shoot video at most. It is probably a matter of where you dive and personal preference.
For myself, I mainly shoot medium angle/portrait of marine animal life. I use wide angle mainly for setup shots.
A lot of photographers love wide angle and fisheye, but for video, I find it a specialty shot. Wrecks, people, fish schools, the rare times I can get very close to a large animal, lush reef landscape scenes.
I ask because I just got a new camera for video. As you know, wide angle underwater lens and ports are expensive. I am debating the expense vs. how often I will use it.