Sorry, the video is bouncing around a fair amount. While the video here is started at Lott’s presentation, you can watch Luciano Lara’s talk before Lott.
Dr. John Lott gave a talk in Brazil on July 5th that discussed the importance of armed civilians in stopping crime. He discussed how police are extremely iImportant in stopping crime, but they have a difficult job and arrive after the crime occurs. He compared crime in Brazil to the US. Next there is a comparison of armed civilians to uniformed police in stopping active shooting attacks.
While the slides shown during the talk were in Portuguese, the English version of the PowerPoint is available here.