At the heart of Gates' address lies the central Global Warming dogma, which dictates that Co2 emitted by human beings are the primary culprit for the unwanted heating of the globe. Since this artificial alleged human-induced heating effect allegedly stands to devastate the planet if left unabated, Global Warming dogma proponents therefore argue that human Co2 emissions must be drastically reduced. As Gates casually addresses the issue, he goes on to state that one way to accomplish this goal is to reduce the global human population.
ERRATUM: To be completely fair and accurate, I should have stated that Gates seeks to reduce the anticipated growth of the human population rather than that he seeks to reduce the current population. I admit that the latter slogan, that is contained in the video, is a bit misleading and I do not want to insinuate that Gates seeks to kill off currently living people. He rather seeks to lower the projected population growth.