Produced by and starring the Blood Diamond actor, the short film actually starts with film-maker Steven Spielberg instructing famous faces from the entertainment world - Will Smith, Harrison Ford and Shia LaBeouf also among them - to say "don't vote" on November 4.
As the celebs struggle to understand the director's strange request, pals Tom and Will are seen complaining to each other, while former 'N Sync member Justin quips: "I can do anything. I was in a boy band, okay?"
A witty exercise in reverse psychology, the video also has the stars sharing screen time with members of the public, who give their personal reasons for voting.
Later Harrison points out the power of individuals, highlighting that just 537 people determined the 2000 election, before Canadian actor Ryan jokes, "There's more Baldwin brothers than that!"
Titled 5 More Friends, the announcement follows Leo's original star-packed 5 Friends clip that debuted at the start of October.