index.html Example File

webenginewidgets/videoplayer/data/index.html
 <!doctype html>
 <html lang="en">
     <head>
         <meta charset="utf-8">
         <style type="text/css">
             #ytplayer {
                 position: absolute;
                 top: 0;
                 left: 0;
                 width: 100%;
                 height: 100%;
             }
         </style>
     </head>
     <body>
         <iframe
             id="ytplayer"
             src="https://www.youtube.com/embed/CjyjEUFn_FI"
             frameborder="0"
             allowfullscreen>
         </iframe>
     </body>
 </html>