A comment someone left on this video (minus the swearing), went as thus:
Your math is wrong. World population is 6,908,688,000, Texas is 7,494,271,488,000 sq ft. Divide it and it's 1084.76 sq ft/person, that's enough for a small house.
If each person learned about 'forest gardening' -- a technique of growing produce -- that would be enough land for each person to live off of. I've learned enough about agriculture and gardening to know that with today's technology (and without it if you live in the right climate) a family can live off of a piece of land the size of a standard mattress. Also, most people would not be living alone, so families would have enough space to own a full-size house.
A family of four would have 4339 square feet of land. If the house has two or three stories, that is indeed plenty of space.
Someone asked me, "What about sewage?"
My response: Ideally, there would be a deep hole dug (about the size of a well, but not deep enough to hit water), for each property, and drain contents would enter into the hole. Soil would be added to the hole regularly and the earth would naturally recycle the waste. But that's just the environmentally ideal solution for sewage.
Technically, there is no reason why underground sewage tunnels couldn't still be built and lead to some place to be "treated" or whatever.
I'm interested in learning more about this topic, so if you have an opinions or facts you want to throw out there, please comment.