The New York-based Feinberg gave the Google-owned YouTube a clean bill of health when contacted by the Herald yesterday.
Over the months since the shootings, Feinberg has forwarded the Herald evidence of the gunman's clip on dozens of Facebook and Instagram pages and, at times, on YouTube.
Copies have been concentrated on Arabic sites. Uploaders have often edited the video - or even disguised it within gaming footage - in efforts to defeat Facebook's filters.
Facebook has said its efforts to beef up its human and AI filters are a work in progress.
They include a new audio filter, designed to detect gunshots.
It says that while some copies have been successfully uploaded that it has blocked millions of other attempts, which are often edited versions.
In May, the social network also introduced a new "one-strike" policy against users who violate its community standards policy, which can see users banned from livestreaming for up to 30 days. Re-offernders can be banned altogether.
At the Christchurch call summit in May, Facebook also put US$7.5 million toward research with three US universities into methods to tackle hate and terror content.
Facebook's VP for integrity Guy Rosen said the money would go to partnerships with The University of Maryland, Cornell University and The University of California Berkeley for: detecting manipulated media across images, video and audio; and distinguishing between unwitting posters and adversaries who intentionally manipulate videos and photographs
