People sometimes get the mistaken idea that if one is good, then 2 or 4 or 10 must be better. When it comes to Bug Bombs, it is best to follow directions. There are plenty of reports of incorrect use of Bug Bombs leading to fires and explosions. In this case the gentleman was lucky he was not more severely injured.
Bug Bombs are formulated with solvents that may be flammable. If the solvent concentration in the air is high enough and contacts a flame such as a pilot light, an explosion can result. Mythbusters has a video that explores the explosive potential of Bug Bombs.
Bug Bombs are popular among people frustrated by their insect pest problems. Many people who use the bug bombs cannot afford to hire pest control experts. Bug Bombs seem simple enough. Just release the aerosol, leave the room for awhile and the bugs will be gone upon return.
Often, it is not that simple. Bug Bombs spread the pesticide throughout the room rather than targeting areas where the insects are concentrated. This leads to overuse of the pesticide or too little pesticide where it would be most effective. Additionally, insects may develop resistance to insecticides and the pesticides will not be very effective. Often people will try one. If that does not work, maybe more would be better? This is more dangerous than most people understand. Pesticides can be useful but they can be unsafe if not used according to directions.