let slider;

var vScale;

function setup() {

  createCanvas(640, 480);

  pixelDensity(1);

  video = createCapture(VIDEO);

  slider = createSlider(1,100,5);

  video.size(width, height);

  video.hide();

}

​

function draw() {

  // background(51);

  vScale = slider.value();

  video.loadPixels();

  loadPixels();

  for (var y = 0; y < video.height; y+=vScale) {

    for (var x = 0; x < video.width; x+=vScale) {

      var index = (x + y * video.width)*4;

      var r = video.pixels[index];

      var g = video.pixels[index + 1];

      var b = video.pixels[index + 2];

      fill(r,g,b);

      rect (x, y, vScale, vScale);

      noStroke();

    }

  }

  }

​