Luckily for them the boat isn't wrecked and the men appear uninjured, but it could have been a rather different story.
The video appears to have been shot from a neighbouring boat. It was posted onto LiveLeak and more recently onto YouTube.
Blast or dynamite fishing, often using home-made bombs, is an easy and effective way of catching fish — the fishermen just pick the dead or stunned fish up as they float to the surface. But the explosion often destroys the underlying habitat and is extremely destructive to the ecosystem, indiscriminately killing large numbers of fish and other marine life and extensively damaging coral reefs. Experts believe blast fishing to be one of the biggest threats to coral reefs, reducing it to rubble in the area of the explosion. Although illegal, it's still commonly used in Southeast Asia and some other parts of the world.