(CNN) A misleading video posted online by British Prime Minister Boris Johnson's Conservative Party Tuesday highlights the challenges voters face as they try to discern fact from fiction in the lead-up to the United Kingdom's historic December election.

The video made a spokesperson from the rival Labour Party appear unable to explain his party's Brexit policy, and came as Facebook faces increasing scrutiny for its unwillingness to fact-check political ads on its platform.

On Tuesday, Conservatives posted on both Twitter and Facebook an edited clip of an interview from the television show Good Morning Britain, that appeared to show Labour's Brexit spokesperson Keir Starmer faltering for words and unable to answer a question from the show's host Piers Morgan.

In reality, Starmer answered the question immediately in the live interview, BBC journalist Daniel Sandford pointed out on Twitter and Morgan confirmed.

WATCH: Jeremy Corbyn's Brexit Minister can't or won't answer a simple question about Labour's position on Brexit. pic.twitter.com/wsxMlUuq9N — Conservatives (@Conservatives) November 5, 2019

"So this happened," Sandford tweeted . "They edited it to add on the last shot in which Keir Starmer looks stumped. But that didn't happen.