Most performers get Gregorian plainchant wrong, this group don't. Listen to the echos(You need the building to make it sond right) and listen to how each individual line speeds up at the start, and slows at the end. Most plainchant performances get this wrong, and turn out a broken, victorian version with a metronomic, regular beat. This is from when plainchant had a period of popularity, but just dosn't sound right. knowing you were bringing up the voice, I had a couple of days hunting for an example, only to find a horde of incorrect versions. this is the most correct I have found

Any idiot can face a crisis - it's day to day living that wears you out.