A explicação é dada pelo Virtual Memories:
Opening of the Holy Year in Santiago de Compostela
2010 is a Jacobean Holy Year (Año Santo Jacobeo) in Santiago de Compostela (the Holy Year is celebrated every year in which the Feast of St. James the Greater - 25 July - falls on a Sunday; thus the frequency is every 6-5-6-11 years). On the 1st of January, the Archbishop of Santiago, H.E. Msgr. Julián Barrio Barrio, inaugurated the Holy Year by opening the Holy Door. This ceremony still invloves the breaking down of the walling blocking the Holy Door by a silver hammer which was unfortunately discontinued at the last Roman Jubilee of 2000 (the booklet of the ceremony is available online, you will be pleasantly surprised to note the inclusion of several pieces of Gregorian chant and polyphony). Here are some images of the ceremony.
The vesting (note the fine antique vestments worn by the Archbishop, the chapter, and the deacons throughout):
The key and hammer used in the opening ceremony:
The archbishop and his cathedral chapter walking to the Holy Door:
The Archbishop knocking upon the door three times with the silver hammer, singing the versicle "Open unto me the gates of justice" etc.
The wall comes down:
The archbishop prays in silence before the newly opened Holy Door:
The deacons wash the newly opened Holy Door:
Msgr. Barrio takes the archiepiscopal cross and enters as the first through the Holy Door:
The procession also included relics of the Apostle:
Towards the end, the famous botafumeiro, the giant thurible of Santiago Cathedral, was swung:
Here is a short video of the opening ceremony:
Image sources: encaminate2010, user "ESPENUCA" of the forum "Ceremonia y rúbrica de la Iglesia española", flickr account of jm salaber