it used to work really well with blackbox,i think something got broken the last few days after the latest drivers, kernel etc. I think we just have to wait for an update of openvix or an update of the blackbox app. In any case, you need to select vu+ transcoding from the blackbox menu.
i think something got changed or messed up with the streaming port on enigma 2. It used to be port 8001 for normal stream and 8002 for the transcoded stream. now on the PC with vlc it looks like the transcoded streaming is using port 8001 aswell.
what you could do in the meantime is use the webif, it works really well in local LAN and the internet if you have forwarded the webif port and the streaming ports. Just make sure you choose "Show Full OpenWebif" at the bottom of the open webif mobile