One of our favorite YouTube clients for Windows Phone goes by the name of Tubecast. Besides being a full-featured, beautifully designed YouTube app for managing and playing videos, it can also DLNA and Airplay stream content to your TV at the touch of a button.
Version 2.9.8 of the app brings some significant viewing improvements, including some ultra-high resolution support! Best part, there are no audio de-synchronizations.
Full story from the WindowsCentral blog...