The manipulated clip, slowed to make Pelosi sound as if she were slurring her words, racked up millions of views on Facebook the following day. It was posted to YouTube, and on Thursday night was given a boost on Twitter when Rudy Giuliani, President Trump's personal lawyer and former mayor of New York, shared a link with his 318,000 followers.

By Friday, the three social media giants were forced to respond to this viral instance of political fakery. How they dealt with the issue, three years after being blindsided by a wave of fake news and disinformation in the 2016 election cycle, may serve as a harbinger of what's to come in 2020.

And for those who had hoped that new technology, stricter standards and the full attention of these powerful Silicon Valley companies might stem the tide of lies, the case of the Pelosi video does not bode well.