The admirable thing about this performance is how relaxed and unstrained the voices are. Simple as it sounds (and in some ways is) this is enormously difficult music. It's easy to make it sound terrible, hard to make it sound good.
1August(UK) the stream is about 11:03 (it says 10:31above). I don't know if is the correct piece or the performers. ~~~~~~~~~ btw the Hilliard pieces are listed here : http://www.last.fm/search?q=%20Hilliard%20Ensemble%20Viderunt%20Omnes&type=track