According to Wikipedia, O come, O come, Emmanuel is a Christian hymn for Advent. While it is most commonly known by that English title, it is in fact a translation of the original Latin, Veni, Veni, Emmanuel.
During the Easter Time, the Gregorian chants of the Ordinary of the Mass are generally taken form the Mass I, also called Lux et Origo. Kyrie (in forma ordinaria) Kyrie (in forma extraordinaria) Gloria Sanctus Agnus Dei
A brief video with highlights of the ordinations of May 2012, 5th in Rome of 35 priests by the Prelate of Opus Dei.
A brief view of the ceremony that took place on Saturday May 26th, 2007 at the church of St. Eugenio in Rome where the Prelate ordained 38 faithful of the Opus Dei to the priesthood: