Any Yahoo Pipes / Regular expressions gurus around?

Ok, want to try and keep this as simple as possible in terms of a question:

In Yahoo pipes I’m using the regex module on a feed in an attempt to extract a URL from the item.description field.

The culprit (source feed) is Facebook’s posted items feed for my own profile. The link it generates in the RSS feed takes you to Facebook, which of course is a walled garden and requires a login.

I’m attempting to pull the actual source item URL (e.g a Youtube video) from the description, in order to then pipe it into the rest of the feed replacing the Facebook link.

The main problem I’m having is not knowing much about regular expressions. I know for instance that if I were to use (.asterisk) it would do a replace on the whole contents of the description. In laymans code I want to <strip stuff here>Just keep the URL<strip stuff here> but don’t know how I’d go about that…

Thanks in advance.