I saw this video yesterday. The pathos is so strong, for me, I almost cried. It's from a kindergarten classroom teacher in a neighborhood south of Monterrey, Mexico.
It's kind of hard to tell what's going on in the video. Apparently during the whole whole time, there is a major gun battle raging outside the window of the classroom, between rival gangs. The teacher is having the children lie on the floor and keeping them calm, using long-practiced safety drills. She's running her video camera the whole time, as she talks to them and even tries to lead the kids in a song, and uses the plot of the song to keep them lying flat on the floor (to catch the chocolate drops raining down). She keeps saying "no pasa nada" [nothing is happening], to reassure them.