How do I know the variable URL of wowz/rtmp by snooping once?

[marrrs]

I watched a livestreaming video and got the URL of streaming video with URL Snooper. but I found that the server URL changes every time the broadcasting is reopened by the same person. like, rtmp://ip address:1935/streampath/streamname(user'sID+random number), the url is fixed but some random number at the end changes every time the user newly start broadcasting. is that some sort of security method to prevent the video from being played out of itself when the user broadcasts a new video? is there a way to find out the changed URL without actually watching the video? plz let me know.