Homage to the Victims of Terrorism on the occasion of the 25th anniversary of the kidnapping and murder of Miguel Ángel Blanco in Ermua

What is being performed here? I know that may sound judgmental and I don't mean it like that. I'd just like to learn more about what's happening.
The first time I ever heard of the ETA was in a Turkish bath, of all places; my friend and I were being chatted up by a businessman who told us that he worked for a company called ETA but he was very quick to assure us that it wasn't the terrorist ETA. Everything about that encounter was just weird so we left. As it turns out it was only a few years after Sr. Blanco was murdered by them, so no wonder he was so quick to assure us that he wasn't part of them.