mrss(Media RSS) feed for drupal 6
MRSS is just an XML. 

There are many Views plugins to export data as XML. Specifically for MRSS, there is Views RSS. Or you can simply use template files to output data with proper tags.

It should be possible to use Feeds XPath Parser module to import MRSS, too.

The Views RSS module is only for Drupal 7 and 8.