That fan trailer is a phenomenal example of what could have happened if cohesive superhero universes had started just a little bit sooner. Borrowing footage liberally from The Dark Knight trilogy, Superman Returns, and Dawn of Justice, the preview shows us a version of Batman V Superman fronted by the predecessors of Ben Affleck and Henry Cavill. If you have seen Batman V Superman: Dawn of Justice, then you already have a pretty clear understanding as to how the whole thing plays out. Batman fears what Superman is capable of, Superman has to contend with the negative public perception of his exploits, and Lex Luthor (Kevin Spacey in this version) is secretly plotting behind the scenes. The trailer even cuts Wonder Woman in on the action for a few awesome shots. All in all, it's pretty badass.