> I'm sure this could be the case but I'm not convinced that their license to the content would be so specific as to require the delivery of the content video/audio together, or must be played in the foreground.

Oh, it is. Licensing is extremely complex, detailing the medium, format, geography, etc. that you can use it on. A license for video doesn't give you any right to stream audio, and vice-versa.

Content licensing agreements are insane, with a nearly-infinite number of restrictions.