Abedi had learned how to make his bomb from a 30-minute film that he watched on YouTube, featuring a balaclava-clad terrorist identified as Muhammad Al-Muhajir speaking in Arabic, but which had English subtitles. YouTube removed the film but, as frequently happens with “flagged” content on YouTube, by the end of the year it was again being shared on Google’s networks, including Google Drive and Google Photos. “What this deeply disturbing video’s reupload shows is that Google has significant gaps in its very recent effort to combat terrorist content online,” said David Ibsen of the Counter Extremism Project, a nonprofit NGO that fights online recruitment of terrorists.