How to secure videos on Youtube or Vimeo?

I want to start an online tutorial through linking videos on Youtube or Vimeo.I want to restrict viewing of my videos to my registered clients only.The videos on these sites are downloadable,but I want to restrict download of my videos.Is it possible with Youtube/Vimeo ? Or is there any other better solution for my project?

On YouTube, you can select whether a video is public, private, or unlisted. If the video is private, only selected people can view the video. Not sure if a video can be downloaded if it is set on private, however. "Unlisted" means a video can be viewed and downloaded by anyone who has the URL. "Unlisted" might work for what you have in mind, but if your registered clients share the URL with others, you won't have control over that.