How the electoral college decides US elections

Donald Trump won the presidency back in 2016 but more Americans actually voted for Hillary Clinton. Confused? It's because America doesn't choose its president by a popular vote, it uses something called the electoral college - which isn't a college but a system. It was devised back in the 1700s and is enshrined in the constitution, but some say it's outdated and needs an overhaul. Selina Downes explains from Washington DC.