[Commons-l] Video licenced CC

[Douglas Pollard]

    I have been downloading some video that is made from old silent film 
movies.  They are licenced cc no derivatives.  Some are remixed.  How is 
this possible?   I am thinking these old films were in the public domain 
or the remixer bought the right to publish them.  How do these clips get 
published under CC.  How does a remixer  get the right  to not allow 
remixing or derivatives?   If he did a voice over it makes sense that he 
has the right to publish his added sound but how the video?
    If you buy publishing rights can you then publish under a CC 
licence. I am trying to figure out what I can use in making a video and 
how it is that I can't use some things and can others.  My video will be 
maybe 70% my own work but I would like to use CC music.some pictures, 
video and sounds, then publish in creative commons.
                                                                         
            Doug