I'm ending up spidering the site:

\r\n\r\n
\r\nwget -r -c --limit-rate=20k -w 5 --passive-ftp --spider --dont-remove-listing \\
\r\n[link|ftp://user:pass@foo.bar.com/|ftp://user:pass@foo.bar.com/]\r\n
\r\n\r\n

Not quite what I was looking for, but it seems to work. Prolly a server-side config issue. Note too that they kicked me out (too fast, too many retries?) first time through.

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