The poem is 800 years old but the music is more recent.

Beautiful!  Great acoustics.   I hear female voices, but don't see any females, maybe they are tenors or falsettos? 

And again, those Icelanders never fail to amaze me with all their talent, from such a small population! 

Iceland does have disproportionate influence and greatness. I'm impressed, too.

And yes, I believe those are falsettos in the video.