Replay Media Catcher is unable to see https streams on the network as they are encrypted.
Therefore make sure your not using https at the start of the address.
For example, in your browser you'll want to change a URL that looks like this:
Facebook is now defaulting to https. You can change this in your facebook settings. Login to facebook and go to Settings > Account Settings > Security. Then disable Secure Browsing. This change will allow you to capture videos from Facebook.