All flash containers are rendered incorrect if they are placed inside iframe. I've reproduced the issue for Qt 4.8.2 build with msvc2010 for default configuration. There is another bug report (https://bugs.webkit.org/show_bug.cgi?id=71950) referring 4.8.0 RC1. The issue is not reproduced for 4.7.4 and earlier. It looks like qt webkit integration performs incorrect coordinates transformation for iframes. To reproduce the issue, please try to open the following web page in the QWebView (with plugins permission granted): https://bugs.webkit.org/attachment.cgi?id=114353
The Qt port has been removed from WebKit, resolving this bug.