How do I utilize custom press with the /feed?

I am attempting to utilize custom press to create a number of custom fields of entry for a video file so it can be aggregated to an MRSS feed. I am attempting to utilize my feed, but am getting a 404 from the validator.

Is there any history of custom press posts having an issue with MRSS feeds?

What would you suggestion to fix this problem? Essentially, I want the custom post to contain a video URL and relevant meta data. The custom posts will then (hopefully) update on the main /feed page.