Can you provide a link to a test page where I can reproduce this? Please see my notes at http://support.jwplayer.com/customer/en/portal/articles/2186238-troubleshooting-creating-a-reproduction-page for more details on what we like to see in a reproduction page.
You can also test in a JW Player preview page by loading the <iframe> source URL directly in your browser. It should load the video on a page with only a gray background and the video title.
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