Ólafur Arnalds Tiny Desk Concert

From the NPR Music site:

It's as if the pianos were haunted. Somewhere about midway through this Tiny Desk, as Icelandic composer Ólafur Arnalds performed on his electronic keyboard, two upright pianos were playing lilting melodies behind him, absent any performer at the keys. And yet these "ghosts," along with Ólafur's band of strings and percussion, put together some of the most beautiful music I've heard at the Tiny Desk, made all the more mysterious through its presentation.