I have to emphasize spoilers across the board on these vids(and in no particular order):
https://www.youtube.com/watch?v=5QgeAEakiJ8
https://www.youtube.com/watch?v=wJFMXjZ3KQA
https://www.youtube.com/watch?v=f0jG42WA3fw
https://www.youtube.com/watch?v=glOr6Y-IyCI
These are all great. I'd like to add this one in particular since it made me feel incredibly sad and ties back to the story in the Binding Coil of Bahamut:
https://www.youtube.com/watch?v=R3kTEy710Ss
The writing in Heavensward is some of the best in the series, markedly improved from A Realm Reborn.
Also helps the new voice cast/direction in Heavensward is on point.