You can´t LARP a medieval mass

This is a Catholic mass, celebrated in 1990 in Endre kyrka, a medieval church building at the island of Gotland in the Baltic Sea. 

Gotland is Swedish territory, and the church at Endre has therefore been Lutheran since the Reformation. Somehow, the Catholic priest Anders Pilz managed to get permission to celebrate a Catholic mass in the church. 

What is even more interesting, however, is that the mass was celebrated according to a medieval liturgy, more specifically the liturgy used in 1450 in the diocese of Linköping. Not being an expert on medieval Church liturgies, I have no idea why Pilz chose that form (Linköping is on the Swedish mainland) rather than any other. 

Note the people in the pews, dressed up to look like medieval peasants! Note also that Pilz is bearded in the introduction to the video, but clean shaven during the actual mass. Apparently, Catholic priests were supposed to shave during the Middle Ages. Even the books used during the mass look medieval - perhaps they are authentic manuscripts from the period in question, or really good reprint editions. 

Since you can´t LARP a Catholic mass (not unless you´re a bloody heathen and blasphemer to boot), the mass itself is the real deal.

ADDENDUM 2021-07-25

Pilz actually explains why the mass is celebrated according to the Linköping form: the island of Gotland formed part of the Linköping diocese.