The Marian antiphon for Advent is Alma Redemptoris Mater. I have chosen a setting by Guillaume Dufay. (I don’t know who the singers are.)

The lyrics:

Alma redemptoris mater,
(Fruitful mother of the Redeemer,)

quae pervia caeli porta manes,
(thou who remains the open gate of heaven, )

et stella maris succurre cadenti
(and the star of the sea, help the fallen)

surgere qui curat populo.  
(people who strive to rise again.)

 Tu quae genuisti, 
(Thou who gave birth,)

natura mirante, 
(nature wondering,)

tuum sanctum Genitorem.  
(to thy holy Creator.)

Virgo prius, ac posterius, 
(Virgin before, and after,)

 Gabrielis ab ore
(From Gabriel’s mouth)

summens illud ave, 
(accepting that Ave,)

peccatorum miserere.
(Have mercy on sinners.)

The YouTube: