I love immersion rc and fat shark stuff because it makes everything pretty easy. Here I am using a 600mw immersion 5.8 video transmitter and a go pro live out cable from readymaderc.com to FPV my Phantom.
After removing the shell of the phantom, you look for some auxiliary power wires and just poke them out so you can solder a JST battery lead onto it. If you have never soldered, buy a soldering station and get started - it's a great skill to have and this is the perfect first project.
I used a dremel tool to cut out a hole in the gopro hd case but you can do it many different ways. Remember to set you go pro on "Upd" so it flips the picture.
If you have any questions or need some help, please feel free to contact me!
Here is a link to the LCD monitor I showed a picture of (confirm you are ordering the right frequencies for your video tx before you order). It has a built in 5.8ghz rx that works with the same frequencies Fat Shark and Immersion RC work on. This little screen is for my video down link when I am flying the s800, but I use it to test my FPV gear as well. When I am flying FPV, I always use my Fat Shark Dominator goggles with the 5.8ghz receiver module, but that is just personal preference.
If you are having issues with rolling shutter / jello in your HD video, try screwing this moongel between your gopro case and the phantom.
If you enjoyed this blog post, please send me a link to what you film and I will post it in the user videos.
Check out the new DJI Phantom VISION. Built in down link, way points, HD cam that records in RAW. Impressive stuff.