This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.
The Camera API allows applications to manage the camera of the device. It allows them to take photographs, record videos, and get information like the focus, the zoom, the white balance, the flash, … It is a priviledged API and can only be used by certified applications.
Note: Except if you are implementing a replacement for the default Camera application, you shouldn't use this API. Instead, if you want to use the camera in your device, you should use the Web Activities API.