The standalone clip, entitled 3am, has been posted on YouTube.
Republican candidate Donald Trump is seen with a copy of a book called Great Speeches by A. Hitler in the video.
When Homer signals that he might vote for Trump, Marge says: "If that's your vote, I question whether I can ever be with you again."
Homer replies: "And that's how I became a Democrat."
Clinton and Trump are set to face each other in the US presidential election, which takes place on 8 November.