How to find stream URLs on a Mac with URL finders, URL Snoopers, URL sniffers, packet sniffers, ...

• To find HTTP URLs with Safari, just click "Window" -> "Activity" and a window will appear with the list of URLs.
  
• You can use Fast Video Download, a Firefox extension, for downloading HTTP streams.
  
• To find stream URLs that use HTTP as well as other streaming protocols, you can use freeware Wireshark.

Streaming media downloading/capturing software that allows to find stream URLs

• Jaksta for Mac allows to find some stream URLs, as well as download flash video, windows media and mp3 streams.
  
• You can run Replay Media Catcher 3.11 for Windows on Mac OS using freeware WINE or WineBottler:
  How to install and run Replay Media Catcher on Mac OS X (Snow Leopard)
  
  The demo version of Replay Media Catcher allows to find some stream URLs as well as download audio/video streams.