iframe mit Dropdown: Wählbarer Inhalt und datumsbezogener Inhalt

<style>
            div {                   
            font-family: Verdana;
            padding: 0px;
            border: 0px solid #000000;      
        }
        .txt3 {
            font-weight: normal;
                font-size: 100%;
            font-weight: bold;
            font-family: Verdana;   
        }
        .txt4 {
            font-weight: normal;
                font-size: 100%;
            font-weight: bold;
            font-family: Verdana;   
                margin-top: 2px;        
            margin-left: 0px;
                color:#000000;
            border: 2px solid #BC401E;
</style>

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>

<script language=javascript>
                var theSelect,theIframe;
                var today = new Date(),
 
            number_of_day = today.getDay();
                $(document).ready(function() {
                //var today = new Date();
                //var n = today.getDay();
                theSelect = document.getElementById('location');
                theIframe = document.getElementById('myIframe');
                theUrl = theSelect.options[number_of_day].value;
                theIframe.src = theUrl;
            });
            function setIframeSource() 
            {
              var theUrl;
 
              if ( theSelect.selectedIndex > 0) {
                  theUrl = theSelect.options[theSelect.selectedIndex].value;
              } else {
                  theUrl = theSelect.options[number_of_day].value;
              }
              theIframe.src = theUrl;
            }
</script>

<form id="form1" method="post">
          <label class="txt3"> De video-testimonial van:
            <select class="txt4" id="location" onchange="setIframeSource()">
              <option value="http://www.alumnei.nl/images/learninglane.jpg">... maak hier je keuze ...</option>
              <option value="https://www.youtube.com/embed/tP4i7CiMHh4">Monique van Neutegem</option>
              <option value="https://www.youtube.com/embed/Bx5Np1wIXYs">Marjon Heintjes</option>
              <option value="https://www.youtube.com/embed/J-NChlqVAgY">Els de Groot</option>
              <option value="https://www.youtube.com/embed/r_UB0rTH7SA">Arthur Alferink</option>
              <option value="https://www.youtube.com/embed/t66K_g-fkFY">Monique Fortuin</option>
              <option value="https://www.youtube.com/embed/8DC-3DiVL4A">Erna Slangen</option>
              <option value="https://www.youtube.com/embed/8Gvu_lgZZAM">Stephanie de Witte</option>
            </select>
          </label>
</form>

<iframe id="myIframe" src="http://www.alumnei.nl/images/learninglane.jpg" frameborder="0" marginwidth="0" marginheight="0" width="580" height="400" allowfullscreen scrolling="no"></iframe>