Anti-propaganda is just propaganda in front of a mirror.

Facebook, Google and Twitter say they’re creating more anti-terror propaganda to combat violent messages at their source.

Source: Facebook, Google tell Congress how they’re fighting extremist content
Google’s Youtube analyzes your past searches and viewing patterns and “determines” if the viewer “may be headed toward extremism”. If so, Youtube presents ads to “subtly contradict” others’ propaganda messages.
Youtube is removing comments from videos that contain hateful content, as determined by Youtube’s “machine learning” algorithms, automatically. Not mentioned here, but Youtube has also gone to “de-monetization” of videos containing video content that Youtube does not like. What Youtube does not like is hard to determine – I watched a video by a photographer showing that Youtube is “de-monetizing” his photography “how to” videos, for no apparent reason.
A related Youtube change effective immediately, is that Youtube channels are prohibited from running advertising if they have less than 1,000 subscribers and at least 4,000 hours of content viewed during the preceding year.
Facebook is supporting “counterspeech efforts” using automated image and language analysis to identify content. Facebook and Google both say they are using propaganda methods to counter program those they think are receiving propaganda from “hateful” or “violent” persons or groups.
Twitter is using “Tweet throttling”, a form of shadow banning, and down marking trending topics that Twitter decides should not be trending.