Ok, I see now - you are using the 'Feed Explorer' module and not the 'News Feeds (RSS)' module where you see this issue.  I'll check that out, it's a different setup entirely.  I know the module is pretty finicky about the structure of the opml file and any customization you do must really be spot on.

So, what I've done to duplicate the issue is use the settings as follows:

In the Feed Explorer Settings area -

For the Content Source - chose the option 'Custom OPML URL/File'

And for the 'Custom OPML URL/File' in the textbox entered the url 'http://skoussouris.googlepages.com/feeds-v2.opml'

After updating, I now see the issue you report.  Now, going over the feed contents again because the opml used must follow a certain structure, and again, if that's not followed or a tag is not understood, it would not display properly as you see.  Let me take a bit of time to go over this opml and I'll get back to you.

Ok, I still believe, that the issue is tied to that particular feed's use of a custom namespace in the item's description element.  I do not think this is an issue with the OPML file.  Now, what is curious to me is that the Feed Explorer module seems to be busted in v04.09.00 and in v.05.00 rc.  I lose the tabs whenever I change the settings for the Feed Explorer's Content Source option.

Of course, this is not related to your issue, but it is preventing me from finding out why this feed is rendering [[description]] instead of the text.  I can't find the source for the Feed Explorer. 

It may be that somehow, the code is jumbled together for both the Feed Explorer and the News Feeds modules, but they are seperate as far as I know, though both share some elements, I did not think they shared code too. 

I'm sorry I can't offer more help, but I think your issue uncovered a bigger issue with the Feed Explorer.  Unfortunately, there is not a seperate Forum for the Feed Explorer module, but I'll post something in the 'Chat About It' forum to see if anyone else is seeing this same thing. I'll keep monitoring this thread, too.