I want to know the answer to the following question:
The Demand a Plan video campaign followed what tragic event?
All the background I'm provided with is that "In December, Beyoncé along with a variety of other celebrities teamed up and produced a video campaign for "Demand A Plan", a bipartisan effort by a group of 950 US mayors and others designed to influence the federal government into rethinking its gun control laws, following the Sandy Hook Elementary School shooting.". Is that enough to answer the question?