The media content tag is really the "content" tag under the namespace http://search.yahoo.com/mrss/. Most bittorrent clients don't support XML namespaces in their generic form. Most clients that support the media:content tag assume that the namespace is called media in the feed, and will not recognize the tag otherwise.
For more information see the media RSS specification.
The media::content tag includes metadata as attributes. The ones relevant to bittorrent clients are url which is the torrent link, and filesize which is the size of the torrent's content (in bytes).
<media:content url="http://featuredcontent.utorrent.com/torrents/WillisEarlBeal-BitTorrent.torrent" fileSize="12216320"/>
The media hash tag provides the info hash of the torrent hex encoded.