He compared the two options Facebook-based companies have: promoting their product(s) via paying Facebook for promotion, or by outsourcing their "like" to "click farms."
What are click farms? Wikipedia says:
A click farm is a form of click fraud, where a large group of low-paid workers is hired to click on paid advertising links for the click fraudster (click farm master or click farmer). The workers click the links, surf the target website for a period of time, and possibly sign up for newsletters prior to clicking another link. For many of these workers, clicking on enough ads per day may increase their revenue substantially and may also be an alternative to other types of work. It is extremely difficult for an automated filter to detect this simulated traffic as fake because the visitor behavior appears exactly the same as that of an actual legitimate visitor.
Watch the interesting analysis behind the 'Facebook Fraud' above. It's only about 8 minutes, but speaks to every major social media platform beyond Facebook, including Twitter and Instagram.