I have spearfished before, never used a bow though. I can say this ....you maim fish pretty badly either way if you don't get a solid shot. Those guys probably wounded far more than they hit solidly.
So I dunno....to me, sort of looks like a brand of fun that hasn't been around for a while and gets revived whenever rednecks get a couple of spare bucks to blow.
I'd have to agree with marmot, particularly on the likelyhood of maiming the fish if you're off in your shot. That being said, the fish they are targeting is an invasive species that has become a huge problem in the states where it has become established. I don't recall what it is called, but it is apparently a predatory species, and reproduces prolifically. Also, due to its habit of leaping high, fast, and far out of the water when there is a disturbance, like a boat going by, they have caused numerous injuries to boaters, and I believe a fatality as well. So while bowfishing might not be a good idea for around here, I don't see any problem with it where this video was filmed, and I'd even be willing to participate if I was in that area. It's pest control.