https://m.youtube.com/watch?v=oUEza10beMY
There are more than one videos of him advocating depopulation. The most famous ones are Mosquitoes and Equation (he has this equation for CO2 = something, and had p representing Population. "It'll will be much easier to tackle p than the rest." ("tackle" meaning "depopulation"))
Edit: you know what, just for you. Probably better than what you were looking for.
https://corbettreport.com/who-is-bill-gates-full-documentary-2020/