I tried “Upload to YouTube” on my two Lumias, when probably after updating to Windows Phone 8.1 the official “Nokia Video upload” app became useless. But, once you use “Upload to YouTube” you will hardly complain.
It is a well-made app and does what it promises. Not only it allows to upload to YouTube in background too, but one can enter Title, Description, category of videos before uploading. It is also possible to control visibility and enter keywords before starting the upload.
The app uses system wide file-sharing contract of Windows Phone 8.1 and hence it appears as as one of the sharing option in case of videos. With its last update it has also added “Voice control to upload last video (English only)”.
In my opinion no other existing app makes it so easy to upload videos to YouTube on Windows Phone or supports so many features and control. We happily recommend it!!