In a YouTube favorites feed, the items look like:
<entry gd:etag='W/"DEMHRn47eCp7I2A9WhNVGUU."'>
<id>xxx</id>
<published>xxx</updated>
<category scheme='http://schemas.google.com/g/2005#kind' term='http://gdata.youtube.com/schemas/2007#favorite'/>
<title>xxx</title>
<link rel='alternate' type='text/html' href='VIDEO PERMALINK'/>
<link rel='related' type='application/atom+xml' href='RELATED URLS'/>
<link rel='self' type='application/atom+xml' href='FEED SELF-LINK'/>
<author>xxx</author>
</entry>
Note the multiple link elements.
My problem is that I need the href value of the first of those, and $(link/@href) in Custom Post Settings returns the value of the last one. I've tried $(link[1]/@href) which seems like it might be correct XPath, but it doesn't work. And since whatever flavor FWP is using isn't really documented I have no idea if it's me that's wrong or the plugin.