If the origin is running Secure Token, you can use the following property on your edges to connect to it.
You can set the property as an Application level property or a MediaCaster level property. You can also set it for individual .stream files if using advanced stream files (json format). This is handy if you have multiple origins that have different settings.
This will tell the mediaCaster to use secure token when connecting to the origin. You don't need to have secure token enabled on the edges.