Thirdy Person Party?!

I wanted to Purchase the Lelianna's song DLC. So I went to the Bioware
website and did what I usualy do. But then something odd happens.
Firefox warns me... "You have requested an encrypted page that contains
some unencrypted information. Information that you see or enter on this
page could easily be read by a third party."

Who is this third
person party? If it is a virus in my computer then fine, I can get rid
of it. But if it's Bioware, should I purchase it? Is it a hacker? I'm
not sure. It has never come up before! I am purchasing via Paypal, but
not even that is safe against skilful hackers no?