May have time to watch this later, but the description sounds like it’s referring to the demographic transition with respect to population growth. While important and a key rebuttal to Malthusian panics such as China’s One Child Policy, it’s actually been known for almost a century.
Poverty, while related, isn’t as straight forward. You can have general increase in the wealth of a nation contribute to a DT while at the same time income disparity, regressive taxation, concentration of capital, regulatory capture, rentier legal regimes and lack of worker protections resulting in an ossified class system which stalls class mobility and creates an abysmal standard of living among the working classes.
In other words, population decline and the trends that can lead to it don’t automatically translate into general welfare.
