I found those two pieces for mandolin and church organ recently. Both pieces are taken from a recording with religious music which was recorded in the 1980s by Benny Ludemann (mandolin) and Klaas Jan Mulder (organ).
Benny Ludemann is a mandolin and guitar player from the Netherlands. He has made many appearances in radio and TV. He is teaching mandolin and guitar and has made a big contribution to the mandolin orchestra association of the Netherlands NVvMO
The mandolin part ist played with tremolo. Please enjoy this rare combination of mandolin and organ.
I have found one other video with Benny Ludemann from a TV show, Benny Ludemann plays the guitar in a piece named 24 Roses. This is the first video in the following playlist about Benny Ludemann:
Playlist Benny Ludemann – Mandolin / Guitar
You can find a note about Benny Ludemann in German here: http://www.mandolinen-orchester-koslar.de/Texte/jury.htm