This article is talking about 2 different things. If you write a simple Flash program that opens a socket to a remote server, you can embed that on a site and use it to identify certain people running through Tor or any other SOCKS/HTTP proxy. It will only catch people who have configured their proxy very poorly. This has been known for well over a decade and it just catches the low-hanging fruit; it's really not an…
To add to this, in Firefox if you use this: http://i.imgur.com/ajT98xC.png , Flash does not obey it. I kinda think Mozilla should put some kind of warning-text on this dialog window to warn uses that it doesn't apply to flash, silverlight or any plugins. This surprised me at first but it makes sense if you think about it. You really have to do a system-wide VPN type thing. Something like this: https://github.com/apenwarr/sshuttle will actually tunnel everything on your PC.