Well, don’t say we didn’t warn you all. Onlookers from the Hong Kong set of Transformers: Age Of Extinction managed to record Optimus Prime (voiced by the legendary Peter Cullen) speaking to the Human Cast as well as to his fellow Autobots. The video is from the rumored scene (now no longer a rumor actually) where the crew had difficult time obtaining permission to film at the proposed location.
As we said before, the dialog contains heavy SPOILERS and may very well spoil the ending of the movie for you. But, for those who wish to be spoiled before the movie, the video can be found after the jump. Remember to act responsibly after watching.