how to draw over a video in P3

I have been trying to emulate something like this sketch: with a few other features as well. i've been able to track the color but have not been successful at keeping the trial it creates as a drawing over the video. I've tried topLayer in P2 without success, and i am now thinking about how i might make the color track a separate object. Below is what I have so far

Any and all insight/ help would be greatly appreciated!!

` import processing.video.*;

// Variable for capture device
Capture video;

// A variable for the color we are searching for.
color trackColor;

float threshold = 25;

void setup() {
  size(640, 360);
  String[] cameras = Capture.list();
  printArray(cameras);
  video = new Capture(this, cameras[3]);
  video.start();
  // Start off tracking for red
  trackColor = color(255, 0, 0);
}

void captureEvent(Capture video) {
  // Read image from the camera
  video.read();
}

void draw() {
  video.loadPixels();
  image(video, 0, 0);

  textSize(12);
  text("pick a tool, click the color, draw yourself a friend", 10, 30);
  stroke(#FFFFFF);

  textSize(12);
  text("press space to save your sketch", 10, 330);
  fill(#FFFFFF);

  // XY coordinate of closest color
  float avgX = 0;
  float avgY = 0;

  int count = 0;

  // Begin loop to walk through every pixel
  for (int x = 0; x < video.width; x++ ) {
    for (int y = 0; y < video.height; y++ ) {
      int loc = x + y * video.width;
      // What is current color
      color currentColor = video.pixels[loc];
      float r1 = red(currentColor);
      float g1 = green(currentColor);
      float b1 = blue(currentColor);
      float r2 = red(trackColor);
      float g2 = green(trackColor);
      float b2 = blue(trackColor);

      // Using euclidean distance to compare colors
      float d = dist(r1, g1, b1, r2, g2, b2); // We are using the dist( ) function to compare the current color with the color we are tracking.

      if (d < threshold) {
        avgX += x;
        avgY += y;
        count++;
      }
    }
  }

  // We only consider the color found if its color distance is less than 10.
  // This threshold of 10 is arbitrary and you can adjust this number depending on how accurate you require the tracking to be.
  if (count > 0) {
    avgX = avgX / count;
    avgY = avgY / count;

    // Draw a circle at the tracked pixel
    fill(trackColor);
    noStroke();
    ellipse(avgX, avgY, 8, 8);
  }
}

void mousePressed() {
  // Save color where the mouse is clicked in trackColor variable
  int loc = mouseX + mouseY*video.width;
  trackColor = video.pixels[loc];
}

void keyPressed() {
  if (key == ' ') { //space bar
  saveFrame("picture-####.jpg");
  }
}

`