Do you want the camera to be powered all the time, or just when the backup lights are on? Does your 6-pin connector have a backup light circuit? You may have to convert to a 7-pin connector.
When I do a project like this, I like to have the wiring diagram for my particular connector in front of me, right next to my voltmeter. Before twisting any wires together I use my voltmeter to check out my plan. Sometimes colors aren't used the way you would think, especially if some of it is made across the pond. The voltmeter is the final verification of what you have.
But yes, red is usually the positive lead and black might be the ground on the camera. Again, trace it with your voltmeter or check the markings on the 9 volt battery.