Along with stills image capture, the iPhone 5's video capability remains largely unchanged from the 4S. Thankfully this means that you can expect videos with good detail, motion and color saturation from the iPhone 5. Using the built in video camera is exactly the same as it was in previous generations. There's not much control available, only start and stop. However, Apple has added a nice feature to the iPhone 5 that allows you to capture an HD resolution (1920x1080px) still frame while continuing to shoot video. This is not a standard iOS 6 feature, and is unavailable on earlier generation iPhones.
Video sample 1
By default, exposure and focus are automatic in video mode but if you long-press the screen you can lock AF/AE on that point. To give you an idea of how the iPhone 5's exposure and AF operate when left to their own devices, take a look at this video. If you look closely at the sky, you will see that its brightness changes fractionally during the clip. This is almost caused by the phone's metering system trying to compensate for the bright white boat moving in and out of the iPhone's metering area, changing the tonal balance of the scene.
Video sample 2
The iPhone 5 is capable of capturing high quality 1080p HD video that rivals most current compact cameras. The videos are sharp and well detailed with a good level of saturation and contrast. Even though the iPhone 5's CMOS sensor is succeptable to the same 'rolling shutter' problems of its predecessors, it's not terribly obvious, as you can see (or not) in this hand-held panning shot.