What does it mean 'to love your neighbour as yourself'?

When Jesus was asked for the basic rules to live by, he gave just two.  One was to love God.  That seems sensible if you believe in a God who loves you.

The second was 'to love your neighbour as yourself'.  That's short but it's not simple and it isn't easy.  So what do other people think about what it means and why it matters?  Take a look at this video where people just like you and me tried to put in their own words.