The content is secured through basic HTTP authentication: you try to access the URL, you're prompted for user pass by your browser, fill submit, and bam you've gotten the resource. These steps can all be condensed by making a request as follows in a normal browser:
http://user:password@host.tld/somethingsnazzy.xml
For HTTP/FTP I've seed simple fetches in Pipes retrieve password protected feeds using a url. The Get Password Protected Feed pipe is one example.
Yahoo Pipes, however, does not support SSL... so while I could make a request like https://user:password@host.tld/somethingsnazzy.xml
from my browser, the pipe will fail. A work around involves using YQL to access the protected resource since it does support HTTPS:
select * from xml where url='https://host.tld/notpassswordbutstillsnazzy.xml'
While a statement like the one above works fine, making a secured HTTP request that includes a username and password still yeilds a 401 error:
select * from rss where url='https://user:password@host.tld/somethingsnazzy.xml'
What gives?