The exclusive clip seemed like a teaser trailer, showing a young girl running across a tundra (where we have previously seen a Death Trooper carrying a childs toy soldier version of a Stormtrooper). It seems to suggest this young girl is Jyn perhaps representing a time when she was orphaned after losing her father to the Imperials?
There were various other quick-flash battle segments, but the big reveal came at the end something large, shimmering and red reflecting off a glistening floor. Is it a sun? A power core?
Then we see the shape of a masked, cloaked figure standing in the reflection and we hear the rasp of a single mechanical breath.
Darth Vader is back. And the Rogue One panel is over.