It's from The Two Towers extended trailer that was added at the end of Fellowship before it left theaters. I capped it from the easter egg on the Fellowship ee.

That's all we have unless the scene shows up on a future boxed set (which seems doubtful since they dropped the Lorien meeting storyline). I went looking for it because Arwen looks radiant. (Presumably Estel does, too, if you could only see his face better!)