How would I get the next page or more results for a feed?

For example, when I go to [Security Now](http://leoville.tv/podcasts/sn.xml) feed page, there is no "next" link of any kind and the url parameter of "page=100" does nothing:

<http://leoville.tv/podcasts/sn.xml>

I get only 1 page of results of about 20 episodes. **However** my Google Reader can successfully retrieve episodes that are earlier than that.