It's funny to think that Google Video didn't take off, and Google had to buy YouTube. Now YouTube is not available for purchase by Facebook. This is interested with the instagram purchase.
By purchasing Instagram, Facebook prevented themselves from being edged out in photos the way Google is shouldering them out in video sharing.
But with Instagram, they wanted the name-brand.
So instead of simply correcting that failure, Google paid $1.6 billion for something it already had.