The song playing is Adiemus

"Each Adiemus album is a collection of song-length pieces featuring harmonised vocal melody against an orchestral background. There are no lyrics as such: instead the vocalists sing syllables and 'words' invented by Jenkins. However, rather than creating musical interest from patterns of phonemes (as in scat singing, or in numerous classical and crossover compositions), the language of Adiemus is carefully stylised so as not to distract the listener's attention from the pitch and timbre of the voice—for example, as in African languages, syllables ending in consonants are rare. The core concept of Adiemus is that the voice should be allowed to function as nothing more than an instrument, an approach that has become something of a trend in recent choral writing (compare, for example Vangelis's score for the film 1492: Conquest of Paradise (1992)). The word Adiemus itself resembles a Latin word meaning 'We will draw near', though incorrectly formed; Jenkins claims to have been unaware of this."

"Adiemus" : http://en.wikipedia.org/wiki/Adiemus

"There are no lyrics, per se, in their music. Karl Jenkins states in the booklets for Songs of Sanctuary and Cantata Mundi that the text is "an invented language". (The word Adiemus itself is not Latin, but is, according to Jenkins, invented as part of his sound-language.) He writes, "The text was written phonetically with the words viewed as instrumental sound, the idea being to maximise the melisma (an expressive vocal phrase) by removing the distraction, if one can call it that, of words"."

"Adiemus FAQ" : http://www.adiemus.f2s.com/

The only thing Finnish seems to be the nationality of the original "Adiemus Singers" who did the vocals on _Adiemus III: Dances of Time_ and _Adiemus V: Vocalise_.