tl;dr: Before developing a product, test the idea by creating a landing page with a feedback mechanism (survey, email notification, newsletter, etc.) then setup an AdWords account. It's a recycled idea that he has re-branded as "Ghetto Testing".
What he leaves out is that this is also a good way to gauge the cost of acquisition. I've seen several products developed that never advertise on AdWords because they discovered after development that the keywords were too expensive to bid on.