I can't seem to add this feed:
http://www.filmspotting.net/atom.xml
or
http://www.filmspotting.net/rss.xml
It comes through as text-only with links to the audio (which opens the browser app). It's totally possible this is a bungled feed, but both Google Listen and ACast were able to grok this feed properly.
I've been trying to hunt down what they use, but cannot find anything.
Additionally, this feed does not show up in the normal podcast search, but does come up when searching for text (which I find odd)
Update: was able to get it working with http://feeds2.feedburner.com/cinecast, which took a while to find.
Is this an issue with DoggCatcher, or with filmspotting?
Those first feeds don't have any enclosure tags which is where podcast should define links to their media.
The third one (which does work for you) has the proper enclosure tags.
As far as the searching goes. The podcast search uses digital podcast as the search engine, and those are manually registered, I guess by the publishers. The news feed search searches against google search api which I think was originally news but seems to now have some podcast feeds mixed in.