The speed of movement is related to the distance of the finger to the center of the small screen. To detect your finger a skin color range has been definited, but if the tracker is not working very well with your finger you can choose another color to track, for example I have created a small cover for my finger using a red color gum wrapper that works quite well.
The color detection algorimth is using hsv colour to extract color selected areas in the picture combined with a blend mode to capture only the objects with movement, it is a good way to have real-time results.
As we do with google maps, we can use videotracker.js. to control any DOM component like textareas, sliders, video players, etc.