Class for managing the thread & callback to do processing of video.
Although this is not formally an interface, it 'could' be an abtract class.
Since Service's are Runnable, and the run function within them manages the
messaging framework, this class is needed to implement 'another' Runnable
run, which calls back to the appropriate method named 'processVideo' - The
complexity of really processing the video is to be implemented in the
VideoProcessor. This class's function is only to manage threads.
It could be an abstract class, and you could derive a myriad of other
implementations, but I would advise against it, and put all the complexity
into the VideoProcessor Service.