The schola director is Nick Gale.
The Mass was celebrated by His Grace Archbishop Peter Smith. The Mass setting (Gloria, Sanctus, Benedictus & Agnus Dei) was Nicholas O'Neill's Missa Sancti Nicolai (2008) - Latin SATB (div) & organ. The Gregorian propers were sung (Introit, Alleluia and Communio - the Responsorial Psalm is sung in English), as was the Solemn Proclamation of Christmas (sung in English to the traditional, solemn Latin tone) and Credo III (sung in Latin). The Our Father was sung to the setting by Rimsky-Korsakov.
The communion motet: James MacMillan's In splendoribus for SATB & trumpet. The Cathedral Girls Choir sang an anthem to Our Lady by Timothy Craig Harrison. The Mass concludes with Alma Redemptoris (simple tone sung by all).
The chant is free, natural, and strong - fantastic sound really. Incredibly, the people are actually singing, and not only the English hymns. Pay careful attention Americans: listen to the final Alma. Listen and weep for yourselves.
In general, Americans will learn a great deal just by watching these videos and seeing how it is done.