Supertube for Windows Phone has been bumped to version 2.8, which implements support for HQ / HD streaming of YouTube videos. The functionality was disabled on all YouTube clients for the platform due to Google altering the access method for said streams. MetroTube was also affected by the change, but has since been updated to enable users to take advantage of high quality viewing.
Should you be a fan of both YouTube content as well as using Supertube to stream said media to your Windows Phone, then this announcement will be warmly welcomed indeed. Unfortunately the fix did take a long time to reach publication, but it's terrible timing on YouTube's part with the festive season well closely approaching when the changes to its system were applied.
You can download Supertube from the Windows Phone Store for $1.29 with trial available.