Check if a movie/zip/audio file is legal
<p>I am running a server with owncloud for a bunch of users.
However, i totally forbid the usage of this cloud for illegal stuff, like movies/audio/album/zip containing tv shows etc.</p>

<p>How can i be sure that users won't store files downloaded from torrent websites ? </p>

<p>Is there a unix binary that can fetch some screenshots from the mkv/avi file, and check whether there is a watermark or a known picture (20th century fox, warner etc.)</p>

<p>I cannot search for weird strange names like 'DVDRIP', since filenames are encrypted.</p>