I have a website that has a draft mode. Someone can login and see what the site looks like to approve it before the public can see it. I have YouTube videos on an account that I
If YouTube isn't working for you for security of your videos, you could consider using FlowPlayer Free to host the videos on your own network and then use the free flash player on your website. This would allow you to make all URLS accessible only by authenticated users.
http://flowplayer.org/download/index.html
Here is an example of their demo running on my local webserver, with the video hosted on a local Apache server.