The url from the dropdown is a url you can share from where no edits can be made...

jmonegro on April 25, 2011 | parent | context | favorite | on: Show HN: Codr.cc - Etherpad meets Pastebin Meets N...

The url from the dropdown is a url you can share from where no edits can be made. For example, for sharing code on twitter, or broadcasting it (any changes from the main url are still seen in real time).