Warhammer: Future Movie Viewing

What interesting things would happen if the Primarch and the Emperor watched footage of the future together?

They will witness the death of heroes, the fall of the vile, the truth of the warp, and that distant, dark future. And what decisions will they make afterward?

(This is a story written by a new author out of love, so the synopsis is inadequate. The story will mainly focus on the Empire and the Primarchs.)