Some interesting text from WSJ article, New Zealand Massacre Video Clings to the Internet’s Dark Corners:
"Those other places include 8chan, an online message board that describes itself as “the darkest reaches of the internet.” Users can post images or discussions anonymously, and anti-Muslim and anti-Semitic material is widespread on the site. On a number of threads created Saturday, unnamed people shared the video and linked to archived versions.
Some users edited and embellished the video, attempting to mimic videogames designed from the point of the view of gun-wielding characters. One version was edited to include sound effects during the times when Mr. Tarrant fired his gun and graphics of bullets and other tools when he changed weapons. Another video added fast-paced background music."