Tidied codwe
OpenCV seems to have an issue reading some mjpeg or mpeg-1 videos (which we need because the original heart videos were in that format). They include a spurious column of wierd data on the right hand side of each frame which I THINK is the encoded header perhaps? Regardless, the feature detector was detecting features within them so I have now restrained the Feature Detector to stay at least 2 pixels away from the edge of the frame.