Why are people protesting in Mexico? – video

Massacres are not unusual in Mexico. But protests have spread across the country since 43 student teachers disappeared after being detained by police in the town of Iguala, Guerrero, on 26 September. We examine why this case – which has raised allegations of police collusion with drug cartels, political corruption and questions over the effectiveness of President Enrique Peña Nieto's US-backed war on drugs – has proved to be a tipping point for Mexicans