Some quite scary thoughts (for those that do not want to watch it).
From android phone google stores everything you let it store. (or just everything, i do not have android phone, so i am not sure). And it stores on public server, Yes you can access all that data WITHOUT login. All security that is there is obfuscated link to your file.
It is not that hard to guess method that they are using to produce those links, i think it is doable. Download your own data, and compare to links that google created. Probably some mixed md5 checksum. THere is more detail about how to attack it at 8:00 in this vid.
So never make pictures on your android phone that you do not want to share. Like your credit card number, or pin, or your naked GF.