During Spain’s Armed Forces celebration this week, an army dance troupe embarrassed the brass by dancing to Michael Jackson’s “They Don’t Understand Us,” a song critical of the police and security forces in general. The soldiers had no idea, but word got out on social media and the backlash among patriotic Spaniards has been intense. This is not the first time public figures have used songs in ways that went horribly wrong. The World’s Gerry Hadden reports from Barcelona.