presence of capsaicin, a compound that, along with capsiate, can propel the body to scorch an extra 50 to 100 calories following a spicy meal.
Extra 50 to 100 calories is a very insignificant amount. Skipping a slice of bread would have similar caloric advantage. This article also does not mention how much chili peppers one must eat to achieve this increased metabolic rate.
Moreover, the link sited actually does not mention anything about chili peppers increasing metabolic rate, it in fact talks about the negative effects of eating chili peppers.