Ambrosian Rite traditional chant. It is different from Gregorian or Anglican chant.
Via: Dappled Things.
Some examples of Anglicans chanting and singing in America:
The Lord is my shepherd: Hylton-Stewart (Calvary Episcopal Church)
This is the day which the Lord hath made: Anonymous [16th Century English polyphony] (Calvary Episcopal Church)
Christus factus est: Bruckner (Calvary Episcopal Church)
Ave Maria: Parsons (Church of the Redeemer Chamber Choir)
O Magnum Mysterium: Victoria (Church of the Redeemer Chamber Choir)