One key tool in the campaign’s appeal to voters was an ad-placing product Facebook offered, called the Dark Post. An ad could be placed in the News Feed of users with whom the message was supposed to resonate, and it would be invisible to anyone outside of that target audience. It was a way to segment a population without its members noticing they had been segmented, a means of perpetuating a state of informational asymmetry, a tool that could be used to divide and confuse.
Ok, this just sounds like a targeted ad that she is trying to describe as if it's something ominous.
