From the video author:

This choir is from Moscow. They were recorded while they were touring through the Europe.  They defiantly are the great bunch with beautiful voices but it looks like this group gathered just for the tour. Nobody saw or heard of them after.  I tried to find them and invite for the tour to US but unsuccessfully.
Chesnokov’s “Gabriel Appeared”
Soloist: Chernegov-Nomerov Egor (choral dir.)Чернегов-Номеров Егор Глебович
Info from Moscow P.I. Tchaikovsky Music Conservatory

From the author:
This is a german folk song from the 16th century. My singing sucks, I still have to rehearse the accompaniment I developed on the guitar. Singing will be next. Maybe I’ll come up with a better version soon.

Comment from poster:
You have to see that the song can be traced back to a time when Martin Luther and the prtestants seceded from the roman catholoc church wich marked the beginning of 100 Years or wars in Europe called the “religious wars”. I believe it was fashionable to ridicule priests in those days.