Some people are deathly afraid of spiders and the fear leads to strange behaviors. Most spiders are harmless. A good whack or sweep with a windshield tool would quickly dispatch most spiders. The gentleman in the video below had the not so bright idea of using his lighter to dispatch the spider. The big problem: the spider was on the fuel cap of his gas tank and he was pumping gas a the time. The basic equation: Gasoline + Flame = Trouble. In this case, the resulting fire was primarily confined to liquid gasoline on the pavement. Safety devices on gasoline pump nozzles include collars to limit volatilzation. The great danger from gasoline is the potential for a fireball created from a vapors/aerosol. The outcome could have been much worse.
This event reinforces the observation that humans are very bad at risk assessment. We often obsess about non-threats and ignore the real ones. This person was concerned about a non-threatening spider which if left alone, would not have caused harm. The real problem of starting a fire was ignored until it was too late.