If I turn off the BD firewall I can start Steam just fine, otherwise I get an error: "Steam is having trouble connecting to the Steam servers." This is with Windows 8.1. My computer with Windows 7, Steam and BD works fine.
I've tried this about a billion times with tons of different BD configurations, trying everything mentioned in the forums related to Steam. I was able to eliminate any type of error message from the firewall log but I still can't connect.
Here is a link to a BDSP file.
BDSP file