Seems like when you click on that button, and enter the site you want to post. Press OK, the text field will blank out. But hit okay again, and there it is, your URL is on the text box where you put your postwhoring materials in... :D

Firewire, I'll take this one.. :P

When you click on the HTTP button it will:

1. Give a name for the link
2. Insert the actual http address.

That's why you might be slightly confused.