This button leads you to the source image through a very complex URL identification. Some people may ask the question "Does well hidden means secure?"
Indeed, there is a strong negative connotation with security through obscurity. However, consider that use of a password is also a form of security through obscurity (only you know the password). In fact, random URL generation is arguably a more secure method than password since most people will re-use the same password across multiple sites to aid memorisation. There is a useful discussion of this here -http://stackoverflow.com/