I know it’s a cover of “Ahead by a Century” performed by Young Voices Toronto. It sounds very Enya-ish.
It just sound “choral”. Or are your referring to the reverb?
More the beat and the general mood. I guess I’d call it “inspirational” with “Afro-Caribbean” overtones, for lack of a better name.
The actual singing (voice production, timbre) I would just call “singing”. To me it sounds natural, rather than heavily trained, such as you might get in, say, operatic or musical comedy singing - let alone the seemingly free-style warbling a lot of singers seem to decorate a tune with.
On second thoughts, if you mean the arrangement (the fact that they’re singing in unison rather than harmony), then I suppose the term “community singing” would fit.
When everybody sings the same part, it is called monophony (as opposed to polyphonic music).
That helps, thanks!