Gregorian "Once in a Lifetime" (partially found music video; 1991)
Gregorian is a German band headed by Frank Peterson that performs Gregorian chant-inspired versions of modern pop and rock songs. Originally it was conceived as a group very similar to Enigma, with breathy female vocals set to strong beats and forlorn Gregorian chants scattered throughout. Their 1991 debut album, Sadisfaction, was recorded in this style. Lead vocals were provided by a duo referred to as The Sisters of Oz. They were Susana Espelleta (Peterson’s then-wife) and Birgit Freud.
There were two singles from Sadisfaction, "So Sad" and Once In a Lifetime. Both songs were successful, but the latter in particular gained widespread popularity and was covered by such artists as Sarah Brightman, Princessa, and Shirley Kwan. However, only the last minute and a half of the original Gregorian music video for "Once in a Lifetime" has ever surfaced on the internet. Since the partial video was uploaded, some have popped up on YouTube that, when judging by the length and the thumbnails, may appear to be the whole thing, but they are fan-made and merely repeat the footage that is available.