Adobe Primere Pro CS6. It's not fun trying to sync two different brands of cameras (the gopro has a slightly strange frame rate so it gets out of sync), but if I had two of the same cameras it's super easy.Can you tell me what editing software you used to get both rear and forward images to show up in one screen? Good clarity from both cameras.
Thanks.
In case you've never used primere before, just put both videos in the timeline (video track 1 and track 2), then double click on the video showing in the preview window and you can resize it and it'll be picture in picture

-Jamie M.