Facebook was strongly criticised for not removing a similarly edited video of the US House Speaker in May 2019.
Facebook has labeled a second manipulated video of U.S. House Speaker Nancy Pelosi as "partly false information".
The edited video was posted by a Facebook user on Thursday and has been viewed more than 2.5 million times.
The 55-second clip was taken from a press conference given by Ms. Pelosi in Washington in May.
Independent fact-checkers have flagged that the video has been "slowed down" and edited to make it appear as though the House Speaker was "drunk".
While Facebook has not removed the video, it will be promoted less by their algorithms and users will be notified if they try to share the content.
But Christine Pelosi, the daughter of the congresswoman, called for the video to be pulled from social media, tweeting "this is garbage".
Facebook was strongly criticised for not removing another edited video of Pelosi, which went viral in May 2019.
In a statement to Euronews, the company reaffirmed its approach to manipulated media.
"Following an incident over a year ago with a previous video of Speaker Pelosi, we took a number of key steps, making it very clear to people on Facebook when a third-party fact-checker determines content to be false and updating our policy to make explicit the kind of manipulated media we will remove," said a Facebook spokesperson.
"As always, when a video is determined false, its distribution is dramatically reduced and people who see it, try to share it, or have already shared it, see warnings alerting them that it’s false."
The edited video of Nancy Pelosi was shared on Facebook with an accompanying caption: “This is unbelievable, she is blowed out of her mind, I bet this gets took down!”
The original video appeared to have been uploaded to TikTok, and other versions have appeared on Twitter and YouTube.
YouTube has confirmed to Euronews that a channel that uploaded the video has been removed for violating policies on elections.
Euronews has reached out to Twitter and TikTok for further comment on their approach against manipulated media.
Under Facebook's policies, videos will only be removed if they have been edited to mislead someone into thinking that someone has said something they did not, or where the video is the product of artificial intelligence.
CEO Mark Zuckerberg has also recently reiterated social media platforms should not be "arbiters of truth".
But the spread of fake news online has renewed scrutiny of how companies are tackling misinformation ahead of the U.S. Presidential election in November.
In March, both Facebook and Twitter labeled an edited video of Democrat candidate Joe Biden, which was manipulated to make it appear as though he was endorsing his Republican rival, Donald Trump.
"In the last six months, platforms have made policies around what they will do with manipulated media like this," said Sam Gregory, Program Director of Witness
"It's not necessarily a bad decision that Facebook hasn't taken it down, but they needed to move much faster to prevent its spread."
Gregory also told Euronews that companies need to be prepared to implement policies on a global scale that can also give users more tools.
"Policies should not just rely on third-party fact-checkers, they should provide tools so that ordinary users can see very quickly that this was a version of an earlier video."
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