Normaal video thumbnail van YouTube -- https://img.youtube.com/vi/<?php echo $youtube_video_id; ?>/hqdefault.jpg
<iframe src="https://www.youtube.com/embed/<?php echo $youtube_video_id; ?>"
srcdoc="<style>*{padding:0;margin:0;overflow:hidden}html,body{height:100%}img,span{position:absolute;width:100%;top:0;bottom:0;margin:auto}span{height:3em;text-align:center;font:40px/1.5 sans-serif;color:white;text-shadow:0 0 0.5em black}</style><a href=https://www.youtube.com/embed/<?php echo $youtube_video_id; ?>?autoplay=1><img src=<?php echo $video_afbeelding; ?> alt='Video Retiwst'><span><?php echo $titel_alt_header; ?><br/>▶</span></a>"
frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen title="<?php echo $titel_alt_header; ?>"></iframe>
#embed #iframe #on click #on place #youtube