Confused. You said impossible to get real ip from vpn, then said there are add-ons that are able to do so? Are you trying to say that there are addons that can get real ip from vpn such as hotspot shield?
No, HotSpot Shield is a VPN Service (not Proxy Service), we can not get real IP.
We may only get real IP from someone who use proxy to access the forum.
VPN is different from Proxy. But both of them are Internet protocols which allow internet users safer to surf the web.