With no official YouTube app on Windows Phone, several third-party apps such as myTube have filled the void by offering a near-native experience. However, it looks like an upcoming version of the YouTube API will enforce restrictions on the amount of information that can be displayed by services like myTube.
According to a statement provided by myTube to its beta testers, YouTube will be discontinuing support for version 2 of its API from April 20, with the next version containing a few limitations in terms of what third-party clients can fetch:
Version 3 does not support getting recent subscription videos. It only supports the "activities" seen on the YouTube homepage. While that does include some subscription videos, it only shows videos that YouTube thinks is important.
It is no longer possible to show the length of a video or number of views in search results, related videos, recommendations and subscriptions.
We're still trying to understand the limitations that will be introduced with the new API, and will share more details as we have them.
Thanks to Piers for the tip!