MediaElement.Stretch将指定视频如何适合其框架 默认情况下，它会拉伸但保持纵横比。 我不确定您希望它如何知道您的屏幕是什么或为何重要。 你能改写一下吗？

MediaElement.Stretch will specify how the video fits into its frame.  By default it stretches but maintains aspect ratio.  I am not sure how you want it to know what your screen is or why that matters.  Could you rephrase?