How do you test for horsemeat?

At the start of 2013, the media was abuzz with stories and reports of horsemeat being found in beef products in the UK and Ireland. But how do scientists find horsemeat within other products such as burgers?

The video below from LGC, one of the labs in the UK which was tasked with testing for horsemeat in food, takes a  look at the methods they undertake to find foreign substances in our food.