• Copyright content
• Owner is not you
• Video is Copyrighted and no one is allowed to put it on a site

The reasons above may be a reason why your Adsense application was rejected. Please THINK BEFORE YOU ACT while writing each blog posts. You should make sure that the post you are about to write isn’t a copied content or doesn’t contain a copyrighted material such as images, videos etc……
These rules not only applicable to YouTube videos but to all sites that offer video uploads and embedding such as DailyMotion, Vimeo etc….