BTW Plutonium IS a natuarally occuring element.
From wikipedia: Trace amounts of at least three plutonium isotopes (plutonium-238, 239, and 244) can be found in nature. Small traces of plutonium-239, a few parts per trillion, and its decay products are naturally found in some concentrated ores of uranium,[43] such as the natural nuclear fission reactor in Oklo, Gabon.[44] The ratio of plutonium-239 to uranium at the Cigar Lake Mine uranium deposit ranges from 2.4 × 10−12 to 44 × 10−12.[45] Even smaller amounts of primordial plutonium-244 occur naturally due to its relatively long half-life of about 80 million years.[
It occurs only in microscopic quantities, which is the point he was trying to make.