You may have all noticed that Windows 8 and RT’s Internet Explorer Metro browser has very limited flash support, and to a lot of users, that is a big deal which is why a recognized XDA developer by the name of Marvin_S has figured out how to get past the restrictions for certain websites which utilize flash. This essentially means that users can access any flash-based website with IE Metro by performing an XML tweak prior to browsing.
Marvin_S explains:
As we all know, Windows RT/8′s IE Metro browser has limited flash support based on a whitelist. However a lot of sites are not (yet) whitelisted and hence do not work as desired. So I did some digging in the whitelist mechanism and found a way to hack it.
To apply the tweak, users must navigate to and open:
C:\Users\[USER_NAME]\AppData\Local\Microsoft\Internet Explorer\IECompatData\iecompatdata.xml.
The syntax used for expanding the whitelist is very straight-forward so users should have no problems tweaking the XML file. This bypass method has not only been proven to work on the desktop versions of Windows 8, but also the RT version found running on the recently released Microsoft Surface.
Source: XDA-Developers