YouTube and Facebook start automatic blocking of extremist videos

YouTube and Facebook are among the sites deploying systems to block or rapidly take down Islamic State videos and other similar material, Reuters reports.

The technology was originally developed to identify and remove copyright-protected content on video sites. It looks for "hashes," a type of unique digital fingerprint that internet companies automatically assign to specific videos, allowing all content with matching fingerprints to be removed rapidly.   Such a system would catch attempts to repost content already identified as unacceptable, but would not automatically block videos that have not been seen before.   The companies would not confirm that they are using the method or talk about how it might be employed, but numerous people familiar with the technology said that posted videos could be checked against a database of banned content to identify new postings of a beheading or a lecture inciting violence.   The two sources would not discuss how much human work goes into reviewing videos identified as matches or near-matches by the technology. They also would not say how videos in the databases were initially identified as extremist.