Do you have a video > 15 minutes? YouTube will increase the 15 minute time limit on select users as long as the content is original. YouTube will allow users who complied with the Guidelines and Copyright rules to upload longer videos.
YouTube will use Content ID to manage and protect copyright material. Content ID is used by every major U.S. movie studio and music label.
To see if you qualify, Click Upload at the top of YouTube website. If a video was previously rejected due to length; go to My Videos delete the one that you previously uploaded then upload it again.