"What do you like to do in the summer?"
"Oh, everyone in the neighbourhood throws a party and some people go into the square to set off explosives."
This is a video from the Festa Major de Poble Sec, which translates from Catalan to something like 'Poble Sec's Big Party'.
Poble Sec is a neighbourhood in Barcelona. Once a year, in July, they have a big party which last for ten days or so. Stages, soundsystems, tables and chairs get put out in the street so that everyone can listen to music, dance, eat food, drink, and have a fine time together.
Similar things happen in most of the neighbourhoods in Barcelona during their festa majors. Drums and explosions seem to be a common theme: the people with the explosives are called correfocs ('firerunners', or something like that); and the drumming group are called Diables del Poble Sec. I don't know much about it, apart from that correfocs are apparently quite a recent tradition, but you can read a bit more here.