安全流媒体链接

I have a problem to secure and protect my video link from direct downloads.

I am trying to make something like this link

http://server1.site.com/videos/123/456/789.mp4?key=0457043013fbd9ebae8ae3

Where in key= I can add user, session, ID, or something else, and in that way protect direct download without the proper key.

http://server1.site.com/videos/123/456/789.mp4

How do I make this work with .htaccess? I am on apache web server and I don't know other way to make this.

This is a good example : this is a stream link and can be downloaded

http://pdl.vimeocdn.com/42891/829/162390948.mp4?aktimeoffset=0&aksessionid=3b9dcceb7a14b3436e0a7bfa0b40126b&token=1369110913_9c3017a9a1bbb77b1ca36c7b7c1eb70f

but this you can't download

http://pdl.vimeocdn.com/42891/829/162390948.mp4