The concept of Flash Mob is relatively new to Spain but the appearances of dancers, singers, players etc to highlight an event or situation is definitely becoming more common in Spain. Many banks have been “occupied” for a few minutes as amateur (usually) performers take central stage.
Here is an office in Seville. The video is sub-titled into English so you get to enjoy the dance AND the collapse of the Spanish banking system!
This video is at Gran Casa Shopping centre in Zaragoza. I can’t promise you that you’ll be lucky enough to see a flash-mob every day as you travel around Spain but they are one of the phenomena of the last 10 years.
Here the flash mobbers are on the beach