Google actually has a form of this, called Inactive Account Manager. You can pick an amount of time and who you want to control your information when you die (or go into a coma?). Pretty awesome, I set mine up already.
Your link seems to have some hidden chars at the end, which is why it's not working (for me, atleast).
Here's the link without the extra chars - https://www.google.com/settings/account/inactive
https://www.google.com/settings/account/inactive