The annual celebration festivities Fuegos del Apostol in Santiago de Compostela are usually a week of music, film, fireworks, cultural programmes and other entertainment and attractions.
July 24 and 25 are the main days. Perhaps you saw earlier great presentations on the facade of the cathedral.
In 2015 this wall presentation concentrated on the other side of the Plaza do Obradoiro.
The gothic facade of the cathedral pyrotechnically rebuilded.
from Nouly (3 months of Walking, El Camino in Winter).
Nouly's own words:
"In the winter of 03/04 I walked to Santiago de Compostela. It took me two weeks to cross Switzerland from east to west. Crossing France from Geneva to St-Jean-Pied-de-Port took 6 weeks and was quite hard: It was cold and often rainy, there are few hours of daylight and it can be difficult to find accommodation. On the other hand everyone in France was very supportive and you form a special bond with the few pilgrims you meet. Crossing northern Spain from mid January to mid February was bliss. There's no real off season for the Camino from Pamplona to Santiago, people who do the camino in winter might be a bit quirkier though - which is all the more interesting. Still freezing cold at times with some snow, but you never spend an evening neither alone nor in a crowded place. Any time of year and wherever you start from: just START WALKING!"