Main thing to take away from the source material is that a supervillain blows up a neighborhood, including a public school, and it prompts the government to put a superhuman registration act in place where superheroes would have to register their identities while getting government training. In the comics, Captain America refuses to register and starts a resistance movement of other heroes who think the act is unjust.
I know this is just the first trailer, but I do hope there's more to it than Bucky. What else is at stake that would make so many heroes risk themselves for Captain America?