Here is what I found in facebook security.
people seems really confused about what is shown in the page and what is inside the page of facebook.
For example,
Suppose your friend share a photo album to you to view and he/she didn't give permission to other. Now suppose you want to show that picture to someone else who doesn't have permission. What you can do is, if you have mozilla or chrome browser, right click on the image and click "view image" then it will give you a absolute link of that photo. You can share that link to anyone you want and there is NO PRIVACY AT ALL. You can do similar tweak in video too. View the source code of video in the facebook. Search for ".mp4" link. Replace %3F and %2F unicode charcter with ":" and "/" character. Now you got the pure link to that facebook which can be share to anyone in the world. The funny thing is, even if you deactivate or close your facebook, it will be there !!! and People can still access your pictures and videos :)..

So be careful when you post something stupid in facebook!!!

Surf Safe