var myImageOn = new Image();
      myImageOn.src = 'http://3d.editura3d.ro/img/start.gif';
    function imageSwap(){
         if(document.mybutton.isOff){
            document.mybutton.isOff = false;
            document.mybutton.src = myImageOn.src;
            document.mybutton.name = "BtnStop";
            MediaPlayer1.Stop();
    MediaPlayer1.CurrentPosition = 0;
}
        else if(!document.mybutton.isOff)
           {
            document.mybutton.isOff = true;
            document.mybutton.src="http://3d.editura3d.ro/img/stop.gif";
            document.mybutton.name = "BtnPlay";
            MediaPlayer1.Play();
            }
         }