Yes you can use this gopro FPV cable to get video out to a transmitter. We also sell another one for the hero 3 that supports power input if you want, and also another cable for the older gopro cameras.
But as @Jim said, it will only transmit SD quality video we only use analogue transmitters right now. There are not realy any cheap options of wirelessly transmitting HD video, although there are some options that are small enough if you have some money to spend!
Attached is an image of the cable connected to a transmitter from another topic posted a while back. Although the cable line up properly with the transmitter, the little clip on the cable will need to be cut off so as it does not line up properly with the one on the transmitter. Its fairly easy to do.
