Why Monty Python Reunited

In July 2014, the surviving members of Monty Python reunited for a live show at The O₂ in London. They only performed together 10 times during the reunion, and then went their separate ways again. So this begs the question: Why reunite in 2014, after decades apart?

A documentary about the reunion answers the question, and posted this 90-second clip on the official Monty Python channel. Check it out:

Note: If you're in a place where you can't watch video, I'll spoil it for you. They needed the money after losing a lawsuit with a Holy Grail producer, who sued for royalties related to the musical Spamalot. There's a decent writeup on Wikipedia.