The video’s caption labelled Mr Biden “a liar who has been ripping our country off for years”.
The article sparked a furious response from the Biden campaign, which said there was no record of any meeting between Mr Biden and Mr Pozharskyi taking place.
Mr Trump and Mr Giuliani have long argued that Mr Biden pressured Ukraine to fire its prosecutor-general, Viktor Shokin, in 2016 because he was investigating Burisma.
Mr Trump and Mr Biden are both holding town hall events today, in the timeslot that would have been used for the second presidential debate if it had not been cancelled.
The Hunter Biden issue and the conduct of social media companies are both likely to come up at some point.