https://www.youtube.com/watch?v=LY6CO6FbH40&list=LLJXU1Ssx3AvDREX_aGs1R0Q&feature=mh_lolz
Someone is deleting high ranked Miku Hatsune(and VOCALOIDS) videos by making false reports that the videos are infringing a copyright.
If your video is deleted by a false report, please submit a counter-notification.
In most of the case, the videos will be restored in a few weeks with the number of views and comments.