A surveillance system uses a flash or other memory to store multiple data streams, each of which includes pre-start signal and post-start signal data. An area of the memory is preferably utilized as a circular buffer, in which a second data stream can be recorded without overwriting a first data stream. Buffers can have sufficient to capacity to capture up to an hour or more of image frames. All suitable methods and apparatus for initiating start and stop signals are contemplated, including for example using a button, toggle or other switch, a verbal or other human interface, and using motion, sound, light or other sensors. It is also contemplated that embodiments can include an interface for altering or otherwise designating a pre-signal size of the recently used segment. Cameras according to present invention can be mounted in any desired manner, including for example in camera boxes, on eyeglasses, and on automobiles or other vehicle.