Watching this footage (which I've just come across) gives me goosebumps.
It comes from a pro-Sandinista solidarity concert held in Nicaragua in 1983, billed as a "concierto por la paz centroamericana." The soundtrack was released as "April in Managua." I used to own the cassette version, which I was given in Honduras sometime around 1988. I practically wore it out listening to it.
Wikipedia tells me that Alí Primera, the singer here, died a couple of years later, at the age of 42, which only adds further poignancy to this video.