GS3 USB video output not working

So I got a GS3 a couple weeks ago and I want to use the usb to transfer video. (My gym has tvs with usb ports that I'm told can take video from an android phone and display it on the tv :)) Anyways, when I use my cord the TV is telling me that there is no video signal. So I did a little googling and it seems that Samsung changes the was the video output works (5 pin vs 11 pin or something) Is this true? Do I need to buy a special cord to do this? If so, what cord?

thanks!

Yes. Most are cables are 5 pin. They make an adapter you can get or there are all in one cables you can get too.