I'm not sure where you're getting /stream/1/ from. The SID is associated directly with a mount point. So /stream/ might be SID 1, /foo/ might be SID 2, etc. I've never seen any situation in which you'd use /stream/1/, /stream/2/, etc. unless you explicitly set the mount point name as such.
Centova Cast doesn't display the SID because it's basically redundant if you know the mount point name. But if SAM Broadcaster needs the SID, it will be numbered from 1 starting with your first mount point on the "Mount Points" tab.