MRSS is short for Media RSS, an extension of the RSS format used for syndicating multimedia files (audio, video, image) in RSS feeds. When you create a smart or manual playlist, a MRSS feed is automatically created. It follows a simple URL pattern pattern and uses the following elements:

• Player Source URL – http://player.field59.com/v4/feed
• User Identification – This will be the identification given to your publishing account and will be the same for all videos and playlists. This should match your account name. This data can come from a root-level field that can be manually entered. It is not case-sensitive.
• Key – This is unique for each playlist.