With Google's own YouTube client, the biggest problem has always been the lack of Closed Caption (CC; a.k.a. subtitle) support. It was in no way possible to display subtitles in a video, not even in the latest iOS version (still) having the client built-in. Not so with the recently-released, updated, iPad- and widescreen-friendly, free(!!) YouTube client (AppStore link), which shows a CC icon, making it possible to activate CC's, in Landscape orientation on all models and Portrait orientation on iPads: