live video editing

int[] xpos = new int[100];
int[] ypos = new int[100];

void setup() {
  size(600,600);
  smooth();
  // Initialize
  for (int i = 0; i < xpos.length; i ++ ) {
    xpos[i] = 0;
    ypos[i] = 0;
  }
}

void draw() {
  background(255);
  // Shift array values
  for (int i = 0; i < xpos.length-1; i ++ ) {
    xpos [i] = xpos[i + 1];
    ypos[i] = ypos[i + 1];
  }

  // New location
  xpos[xpos.length-1] = mouseX;
  ypos[ypos.length-1] = mouseY;

  // Draw everything
  for (int i = 0; i < xpos.length-1; i ++ ) {
    noStroke();
    fill(255-i*5);
    ellipse(xpos[i],ypos[i],40,40);
  }
}

This code by Daniel Shiffman. I want to create this effect on live video. I am new in processing.

Instead of a circle I want to show some frames with a particular interval. After that It should gonna fadeout.

I tried some logic but it wont work.

I wish your help.