The Veritasium YouTube channel has built up a loyal following with its fascinating collection of science videos, but its latest release takes a turn into the shady industry of Facebook likes. In a nine minute video, Veritasium creator Derek Muller explores Facebook click farms and uncovers the process through which buying likes actually ends up hurting advertisers.

As Muller explains, there are two ways to ‘buy’ likes: Directly, through illegal third-party click farms, or legally, through Facebook’s “post promotion” feature. Judging from this dichotomy, you would assume that likes purchased legitimately (through Facebook) would come from actual profiles of real, live people. As Muller shows, this is not the case. Instead, when he purchased $50 worth of Facebook advertising, most of his new likes came from developing countries like Egypt and India (where click farms are common) and did not engage with his updates.

As Muller explains, this creates a perpetual cycle for those who buy likes: They attempt to increase the exposure of their posts, fail to see the result they desire (thanks to many bought likes coming from fake profiles), and then are encouraged purchase more likes. This ends up actively hurting page owners, since Facebook only sends out updates to a fraction of fans, and uses those fans’ responses to gauge interest in the selected post. If the initial group contains mostly fake likes, the post is much more likely to get buried.

This is all just a summary of Muller’s presentation, which is brilliant from start to finish and absolutely worth watching:

The bottom line is simple: Don’t buy Facebook likes.