Some more info as Bay updates us on Transformers:
The unreleased ad (Prime speaks) that was posted on youtube was a test that European were making with the ads. The clip where OP was "speaking," lets just say that it wasn't OP or Cullen speaking. It was something the European studios added on their own. In fact, it was a test shot.
They are referring to the infamous youtube clip that all the hardcore nerds (you know who you are) got their panties in a knot about how Optimus Prime had lips :)