When he says “demeaning content behind the victim’s back”, ...

“Aided by the rise of new digital communication technologies, as well as an Internet that allows messages and images to be distributed anonymously, episodes of cyberbullying have become much more common. According to a 2013 review of cyberbullying research, online harassment can take two primary forms: direct cyberbullying in which threatening or insulting messages or images are sent directly to the intended victim and indirect or relational cyberbullying, which involves the spread of rumours and/or demeaning content behind the victim's back. And there are a variety of ways for cyberbullying to happen, including texting, emails, or through posts relayed through social media sites such as Twitter, Facebook, and Instagram.”

(What Makes Cyberbullying So Popular? By Romeo Vitelli. Psychology Today. Available in https://www.psychologytoday.com/us/blog/mediaspotlight/201808/ what-makes-cyberbullying-so-popular.)