Live Video object tracking
OpenCV is a good repository of computer vision resources. An example of how to select and track a region of interest is given here: https://docs.opencv.org/3.4.0/d2/d0a/tutorial_introduction_to_tracker.html 


Also see an example blog post here: https://www.learnopencv.com/object-tracking-using-opencv-cpp-python/ 

More state of the art research results and code in visual object tracking are maintained at the following website: http://www.votchallenge.net/vot2017/trackers.html