I'm having a very strange problem with the IE9 browser, when viewing pages that have their document mode configured to anything other than "IE 9 Standards".
If an HTML page has set its "document mode" to anything other than "IE9 Standards", and the page embeds a Youtube video with an <iframe> tag, then this problem occurs:
Any embedded Youtube videos will show only as a black square (of appropriate size) with a red "play" button in the middle, and the play button does nothing.
Here's an example of a page that trips this problem for me: utechu.blogspot.ca/2011/11/how-to-unlock-samsung-galaxy-q.html
If you hit F12, you can see that the default "Browser Mode" is IE9, but the "Document Mode" is set to IE 7 Standards on that page.
If I use the debugging console tool from the F12 key, it immediately shows this error on the page: "SCRIPT438: Object doesn't support property or method 'forEach'"
But if I then click and change the Document Mode to "IE 9 Standards", the page reloads, and then the videos embed and play perfectly!
This only happens when the embedded video on the HTML page is tagged by an "<iframe>" call. Very oddly, if the embedded video is called by Youtube's old-style "<object=>" tag, then the video will play perfectly, even when the HTML page sets document mode to IE 7 Standards (or Quirks, or whatever). I'm only vaguely familiar with Youtube's tech, but I'm guessing that <iframe> tags force IE9 to use HTML5 to view the video, while "<object="> does not. So maybe what this comes down to, is that HTML5 will not render on my particular computer's IE9, if the Document Mode of the web page is not set to IE 9 Standards.
This only happens on my one computer. Any other machine running IE9 views these pages (like the above link) just fine.
I have tried all the "easy" ideas, including clearing the IE9 cache, then uninstalling and reinstalling Adobe Flash Player, and then even uninstalling IE9, going back to IE8, then reinstalling IE9. I'm at my wits end. What's going on here??? Please help, if anyone has an idea!