A friend of mine, a Parish Priest in the Archdiocese of Westminster, sent me a link to this video earlier today. It is an extract from the 1944 film Christmas Holiday starring Deanna Durbin and shows part of a Christmas Mass. It was filmed at St Vibiana's, the former Cathedral of the Archdiocese of LA which was damaged in the Northridge earthquake of 1994 and sold to the city. St Vibiana's has since been replaced by the new Cathedral of Our Lady of the Angels. The music in the clip includes Puer natus in Bethlehem, the Kyrie from Licinio Refice's Missa Choralis and Adeste fideles.
Our grateful thanks to a kind NLM reader who remastered the clip and made it available to us.