The video circulated throughout much of Sunday without a response from the social media networks. After users flagged the video to Twitter on Sunday, the company said it had determined that the video violated its rules against synthetic and manipulated video and labeled the video as manipulated content. By that point, it had been viewed more than five million times and retweeted more than 20,000 times.
It was the first time that Twitter applied a policy announced in February against fake and misleading videos. Facebook, however, did not remove or flag the video as misinformation, angering the Biden campaign.
“Facebook’s malfeasance when it comes to trafficking in blatantly false information is a national crisis in this respect,” Greg Schultz, Mr. Biden’s campaign manager, said in a statement.
“It is also an unconscionable act of putting profit above not just our country, but every country,” he added. “Facebook won’t say it, but it is apparent to all who have examined their conduct and policies: They care first and foremost about money and, to that end, are willing to serve as one of the world’s most effective mediums for the spread of vile lies.”
Mr. Biden’s campaign has complained about false online ads by Mr. Trump’s re-election campaign before, beginning in October with an ad on Facebook and other social media outlets that asserted that Mr. Biden had bribed the Ukrainian government to stop an investigation into his son.
Facebook refused to remove that video, saying false speech by politicians and their campaigns was permitted as an important facet to political discourse. Mark Zuckerberg, the chief executive of Facebook, reinforced that view with a speech on free expression at Georgetown University in October, in which he said that political speech was one of the most vetted forms of discourse and that it was important for the public to hear from politicians, including lies.
In a statement on Monday, Facebook said, “Fact checkers rated this video as partly false, so we are reducing its distribution and showing warning labels with more context for people who see it, try to share it or already have.”