Why 100%? Well, right now there are many websites out there that will not allow their users to watch them while in incognito mode. They will either force them to become visible again or to pay a lesser or greater fine in order to view them. Google, being a wannabe good uncle that it wants us to see it as, works on creating an incognito mode that bypasses all those limitations. This new solution is currently tested in Chrome Canary; if you want to learn how it works, check out this site by Techdows.