If you only do the grove gate fight the ending cinematic only mention you discovered the Grove and the Tielfings (which you did), then it skip to the dark fortress part.
If you watch the video from the start, you'll see how he bypassed the grove gate fight.
I think that line and the fortress line are the start and finish trigger with all the permutations in between, but maybe you can get a boat -> fortress narration if you skip the grove through sequence breaking?
