Very cool, indeed, but not a choir (see below). They're from Finland and their name is "Rajaton." This particular video is from the 2004 Musica Sacra in Marktoberdorf. Their website is:
And technically, they're not really a "choir," in that they sing one to a part. They're a "vocal ensemble." (Pedantic perhaps, but this *is* ChoralNet and we wouldn't want to unintentionally blur the definition of what a "choir" is.)
"A term used for groups of singers performing together, usually in parts with more than one singer per part."
Online, definitions with the word "must" are elusive, but yet there are clear, authoritative statements that a "choir" involves having more than one singer on a part, such as this one:
Book: "The Choral Singer's Survival Guide," by Tony Thornton, page 1 -- "choral music--music written for more than one singer on a part--is still thriving"
And here's one from an online dictionary that's quoting Encyclopædia Britannica:
"body of singers with more than one voice to a part"
There's no qualifier in that definition, so there you are. The distinction isn't always taught to choral directors in training--I didn't become aware of it until grad school, but it's a distinction nonetheless. Anyway, I have personally processed thousands and thousands of link submissions to ChoralNet's directory of choir websites, visiting each and every site, and the sites from vocal ensembles don't call themselves choirs, so it's a consensus-based usage of the terminology throughout the worldwide classical (and church) music community.
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