Interesting you should mention the GoPro. I use one diving from time to time after my buddy spoke about using his. Not so much for the videos because as he put it they never turn out very good (takes a bit of skill especially under water) but because on his down days what he sees when he reviews them.
Hard to explain but diving you are always doing things. Checking air, gear, dive buddy's gear, air, and then observing and, well, diving. You see things and processing all this to be safe and what not. After the dive you are talking to your buddies and say hey did you see this, no. Well, did you see this? Yeah, I did, etc. Then he said he pulls up the video months later and watches it from his computer or laptop and suddenly you see things that you didn't on the dive.
One example he showed me a photo of was this large tube sponge with a arrow crab living it it during the day to hide. Really great color, depth, and contrast. Upon first look I was like so cool. He said look again, I did. I said yeah, really cool. He smacked me upside the head and said look again. I did. Now I see a very large moray eel head on the side of the sponge and rock that I didn't see before. It blended in so well. He said exactly, I didn't see it nor anyone on the dive. Just the silly crab :)
So to your gopro point. A lot of divers take them for this reason and review after. They also will use it for some animals that they know are being watched. We have a few in Monterey that are and people send the data off to the department asking.
So yeah - very cool. Not just death and destruction but also science.