As on many mobile devices, Internet Explorer on Xbox doesn’t support browser plug-ins (such as Adobe Flash). Learn how to access the “mobile” version of a website, which may not require a plug-in.
Configure Internet Explorer to use mobile pages
If webpages are blank or notify you that a plug-in is required, you can try configuring Internet Explorer to request the mobile version of webpages you go to. This may help if the page uses Flash, Java, Silverlight, or other plug-ins, which Internet Explorer on Xbox does not support.
Press Y to display the Web Hub.
Select the Settings icon on the address bar.
Select the Use web pages formatted for mobile devices check box.