AngularJS – Marcação personalizada

var app = angular.module("app", []);
 
app.controller("AppCtrl", function() {
    this.random = Math.random();
});
 
app.directive("app", function() {
    return {
        restrict: "C",
        controller: "AppCtrl as app"
    };
});
 
angular.bootstrap(document.getElementById("container"), ["app"]);
<!DOCTYPE html>
<html>
<head lang="en">
  <meta charset="utf-8">
  <title>Egghead Videos</title>
</head>
<body>
 
  <div id="container" class="app">
    {{app.random}}
  </div>
 
  <script type="text/javascript" src="//ajax.googleapis.com/ajax/libs/angularjs/1.4.0-beta.6/angular.js"></script>
</body>
</html>