Yahoopipes Picasa feed accessing at runtime results

I am using YahooPipes code to parse a cross domain picasa feed in its minimal form. I would like to know how to read the media:group - media:thumbnail tag in the xml retrieved at Runtime.

for (var i=0; i<feed.value.items.length; i++){tmp+='<a href="'+feed.value.items[i].link+'">';tmp+=feed.value.items[i].title+'</a><br>';if (feed.value.items[i].description) {tmp=feed.value.items[i].description;}

How will I retrieve at runtime I mean to say

tmp+=feed.value.items[i]......media:group.media:thumbnail[0].url 

here...

The sample feed is here:

http://picasaweb.google.com/data/feed/base/user/mdalthaf786/albumid/5481762720476791505?alt=rss&kind=photo&hl=en_US&fields=item(media:group(media:thumbnail))&thumbsize=288&go.xml