This is very useful method to crack any hidden passwords of facebook .,gmail.,yahoo.etc.. the user always stores the password to easy login next time.! but when you open the login page it shows encrypted password which is hidden so now im gonna tell how to Decrypt the password..
step 1- go to login page of facebook or gmail anything..
step 2- right click on password box and select inspect element----->>then seect the password box
it shows html coding there in password field re-enter it as "text" without quotes as like below image

