Same issue here with Internet Explorer only.
Work perfectly under Chrome & Firefox, but under IE the div is closing without stopping the video from Youtube working…
Here’s a way I put the link:
echo "<a href=\"https://youtube.com/embed/".strrev($rest)."?autoplay=1\" class=\"thickbox\"><img width=\"".$settings->width."\" height=\"".$settings->height."\" src=\"https://img.youtube.com/vi/".strrev($rest)."/hqdefault.jpg\"></a>";
