We would like to add an MPX feed to Autoblog

We would like add the functionality to ingest MPX videos with Autoblog. Here is an example: http://feed.theplatform.com/f/9kcGiB/0HTdJ_FzdxbY. Under each item we have one or more of a property <media:thumbnail>. How can we access that programatically from our addon?

I know it has to be something like $item->media....