Which mode in windows 8 are you trying to watch the content? Please try the method below.
When using the Metro version of Internet Explorer, not all Flash content will appear. This can be corrected by switching to the desktop version using these simple steps.
Please click here for an HTML5 version of this video: YouTube HTML5 HD Link
1. Hit the Windows + Z key or right click anywhere in the browser to bring up the IE controls and then click the tools button
2. In the menu that appears, select "View on the desktop"
Internet Explorer will relaunch in desktop mode and all Flash content should appear.