',pluginName, ...)
   vr = videoReader(url,pluginName, ...)
     Opens the file using the manually specified plugin implementation.  
     Available plugins include:

     'DirectShow': preferred method on Windows
       - Only available on Windows
       - See INSTALL.dshow.txt for installation instructions
       - Can load virtually any video file that can be played in
         Microsoft's Windows Media Player.  Note that the correct codec
         must be installed to read a file.  For example