Heavensward Ending (Spoiler)

[Kauthryn]

True, he was used as a stand in in patch trailers as well before. However, these videos don't exist in game in that form. In game it's us who are there. In fact, the launch trailer and the cinematics shows the derplander crossing the steps of fate in two different ways. I'm going to take the video viewable in game to be the valid one and conclude that the launch trailer is not canon from the perspective of my character.

TL;DR. Having the derplander in the scenes shown in the launch trailer contradicts your personal character's story. Having derplander in the cinematics, does not.

How you deal with facts isn't my concern.
I was only showing you the factual evidence.

It is impossible for SE to put "your character" in these videos.