The Xbox One's YouTube app is finally getting updated tomorrow to support uploading of Game DVR clips from the hardware's Upload Studio. Currently the app on Xbox One is "limited" to browsing Youtube with all the Kinect fixings.
The Upload Studio supported Xbox Live sharing and OneDrive storage since Xbox One's launch, but after the update you'll also be able to share Game DVR clips to your YouTube channel.
Since the Game DVR at most captures five minutes of your gameplay (in 720p and 30fps), don't expect to be pushing any big video walkthroughs from the YouTube app. On the other hand the functionality is something extra that the Xbox One can boast in its favor, as built-in YouTube sharing isn't on the cards for the PS4 even after the big system update hits. That's not the only improvement coming; you can add YouTube channels to your OneGuide and view YT videos in Snap Mode following tomorrow's update.