American Organist Organist Jeff Davis improvises on Divinum mysterium in the Catedral de Santa María La Real de La Almudena on the Grenzing Pipe Organ. This was filmed as part of the PipeDreams tour of Spain in 2013. An incredible tour of pipe organ in Spain lead by Michael Barone.
Andres Cea is a fine organist from the South of Spain. Here is a segment of an improvisation he played to demonstrate the organ. The organ was built by C. Familia Echevarria in the 18th century. It was restored in 2011 by the Grenzing organbuilding firm.