This improvisation is part of the private Christmas concert, which I played at home for my family and neighbours back in 2013 (so these were my first steps with GrandOrgue). Since I signed up at ContreBombarde after Christmas in 2014, I found that it was too late to post it then and decided to postpone the upload until this year's Advent season -- now here it is.
For all those who have not yet discovered the full concert recording on YouTube, it is now the time to reveal it before Christmas is over... ;)
I added the video ID to all the related pieces now. Maybe anyone of you will find another piece from the concert (s)he likes (or dislikes).