It seems to me they're saying they've lived such good lives it's now time to commit suicide for the benefit of future generations! Is there any other conclusion one can arrive at? Which is their choice of course, but it also seems to me they want others to accept the same fate.
First of all, her statement about humanity becoming so large the Earth can’t sustain it is false. Secondly, if we really want to control the size of the world’s population we need to do one thing that will successfully reduce population growth. Build strong, stable economies!
In economically successful countries the population growth slows, and in some cases isn’t even replacing the current population. Economic security is the key to population self control, and without the schemes of morally defective misanthropic activists.
One more thing - did anyone notice the logo at the bottom right hand of the video? It's the Agenda 21 logo for the United Nations Division for Sustainable Development. Amazing! I keep hearing that's just a conspiracy theory?