Information from the Official Adobe site about this issue
The issue is when you embed a youtube link:
https://www.youtube.com/embed/kRvL6K8SEgY
in an iFrame, the default wmode is windowed which essentially gives it a z-index greater then everything else and it will overlay over anything.
Try appending this GET parameter to your URL:
wmode=opaque
like so:
https://www.youtube.com/embed/kRvL6K8SEgY?wmode=opaque
Make sure its the first parameter in the URL. Other parameters must go after
In the iframe tag:
Example:
<iframe class="youtube-player" type="text/html" width="520" height="330" src="http://www.youtube.com/embed/NWHfY_lvKIQ?wmode=opaque" frameborder="0"></iframe>