The DMCA provides a framework for copyright holders to report alleged infringements and request the removal of infringing content. In response, the IA likely removed the Iron Man 3 upload to avoid further copyright infringement claims.
Archive.org has a robust collection of vintage movie trailers. Fans have uploaded every teaser, Super Bowl spot, and international trailer for Iron Man 3 . Watching these low-resolution, sometimes grainy 2013 TV spots is a fascinating time capsule. You get to see the marketing before anyone knew about the Mandarin twist—back when Ben Kingsley looked like the ultimate villain. iron man 3 internet archive
"iron man 3" AND mediatype:(movies)