The method OpenNextFrame will request a frame from the video stream. The method is provided
with a parameter that is the number of milliseconds to wait before a frame becomes available. If the
camera cannot produce a frame in that time, the OpenNextFrame method will return a null result.
This allows you to prevent a program from getting completely stuck if a new frame isn’t available.
The great thing about this way of working is that the program will only request a second frame when
it has finished processing the first one, and so on. The best way to do this is to make a loop that
repeatedly fetches frames and displays them, before moving on to the next one.