The beginning is the opening song of Johann Sebastian Bach's Christmas Oratorio. He composed it in my hometown Leipzig as choir master of the St. Thomas Choir. To this day, the choir performs the Oratorio every Advent in St. Thomas Church. Your video reminds me of home and of better days. If you can, perhaps watch a video of the entire Christmas Oratorio with an English translation its beautiful lyrics. I really recommend getting an English translation of these beautiful lyrics by Bach, but I am not quite sure if the beauty and depth comes across well in English. The Oratorio's profound Christianity and its hope in Our Saviour is uplifting and moving. Enjoy and God bless!