Embedding Youtube videos within your apps is typically done with a UIWebView, but it is possible to do play Youtube videos within an MPMoviePlayer.
The trick is getting to the MP4 video file provided by Youtube, and I’ve come across a library that does this automatically for a provided URL.
You simply need to specify the URL, and size of the player using this library where you would otherwise be using a UIWebView to play the videos, and if the MP4 file can’t be reached a UIWebView is used.
Included with the library is a working example.
You can find the library known as PSYoutubeExtractor on Github here.