Apple trailers in fullscreen: save as bookmarklet, start a trailer video on trailers.apple.com, run the script.

atf.js

javascript:(function(){try{var video=find('.moviePanel object embed');var origWidth=video.width,origHeight=video.height,origStyleWidth=video.style.width,origStyleHeight=video.style.height;onEnterFullscreen(function(){video.width='100%';video.height='100%';video.style.width='100%';video.style.height='100%';});onExitFullscreen(function(){video.width=origWidth;video.height=origHeight;video.style.width=origStyleWidth;video.style.height=origStyleHeight;});fullscreen(video);}catch(e){}function getVideoSize(video){return[video.width,video.height,video.style.width,video.style.height];}function setVideoSize(video,size){video.width=size[0];video.height=size[1];video.style.width=size[2];video.style.height=size[3];}function find(query){return document.querySelector(query);}function isFullscreen(){return document.fullscreenElement||document.webkitFullscreenElement||document.mozFullScreenElement||document.msFullscreenElement;}function onFullscreenChange(cb){document.addEventListener('fullscreenchange',cb,false);document.addEventListener('msfullscreenchange',cb,false);document.addEventListener('mozfullscreenchange',cb,false);document.addEventListener('webkitfullscreenchange',cb,false);}function onEnterFullscreen(cb){onFullscreenChange(function(){if(isFullscreen())cb();});}function onExitFullscreen(cb){onFullscreenChange(function(){if(!isFullscreen())cb();});}function fullscreen(el){if(el.requestFullscreen){el.requestFullscreen();}else if(el.msRequestFullscreen){el.msRequestFullscreen();}else if(el.mozRequestFullScreen){el.mozRequestFullScreen();}else if(el.webkitRequestFullscreen){el.webkitRequestFullscreen();}return el;}})();

atf_src.js

try {
  var video = find('.moviePanel object embed');

  var origWidth        = video.width,
      origHeight       = video.height,
      origStyleWidth   = video.style.width,
      origStyleHeight  = video.style.height;

  onEnterFullscreen(function() {
    video.width        = '100%';
    video.height       = '100%';
    video.style.width  = '100%';
    video.style.height = '100%';
  });

  onExitFullscreen(function() {
    video.width        = origWidth;     
    video.height       = origHeight;     
    video.style.width  = origStyleWidth; 
    video.style.height = origStyleHeight;
  });

  fullscreen(video);

} catch(e) {}

// ---

function find(query) {
  return document.querySelector(query);
}

function isFullscreen() {
  return document.fullscreenElement ||
         document.webkitFullscreenElement ||
         document.mozFullScreenElement ||
         document.msFullscreenElement;
}

function onFullscreenChange(cb) {
  document.addEventListener('fullscreenchange', cb, false);
  document.addEventListener('msfullscreenchange', cb, false);
  document.addEventListener('mozfullscreenchange', cb, false);
  document.addEventListener('webkitfullscreenchange', cb, false);
}

function onEnterFullscreen(cb) {
  onFullscreenChange(function() {
    if (isFullscreen()) cb();
  });
}

function onExitFullscreen(cb) {
  onFullscreenChange(function() {
    if (!isFullscreen()) cb();
  });
}

function fullscreen(el) {
  if (el.requestFullscreen) {
    el.requestFullscreen();
  } else if (el.msRequestFullscreen) {
    el.msRequestFullscreen();
  } else if (el.mozRequestFullScreen) {
    el.mozRequestFullScreen();
  } else if (el.webkitRequestFullscreen) {
    el.webkitRequestFullscreen();
  }

  return el;
}