Bookmarklet to enable AirPlay on iOS 4.3 devices see http://jamesclarke.net/notes/enable-airplay-on-all-web-video

airplay.js

//Enabling AirPlay on iOS for all videos
//James Clarke <http://jamesclarke.net>
//See <http://jamesclarke.net/notes/enable-airplay-on-all-web-video> for a description.

//in one line
javascript:[].slice.call(document.querySelectorAll('embed,video'),0).map(function(e){e.setAttribute('x-webkit-airplay','allow');e.setAttribute('airplay','allow')});var w = window.open('about:blank');var d = w.document;d.open();d.write(document.documentElement.innerHTML);d.close();

//human readable
javascript:[].slice.call(
  document.querySelectorAll('embed,video'),0).map(
    function(e) {
      e.setAttribute('x-webkit-airplay','allow');
      e.setAttribute('airplay','allow')
    });
var w = window.open('about:blank');
var d = w.document;
d.open();
d.write(document.documentElement.innerHTML);
d.close();

Added write up on my site. Bookmarklet to enable AirPlay on all web videos.