There have been three pretty amazing Age of Ultron trailers so far (even if they do sort of give away the whole plot). So someone mashed them up, in pretty-close-to chronological order, and viola!
I have to admit this kind of seems to spoil the plot and movie, but there is definitely still a lot of movie we haven't seen! Official trailers these days spoil vast amounts of movie content. It's why so many people refuse to even watch trailers anymore. TV commercials for shows spoil plot of episodes all the time as well.....I'm thinking maybe I'm going to have to start passing on trailers as well!
Either way, cool idea, and now I don't have to wait any longer to check out this movie!