I'm not sure the best way to approach that issue so I'll defer to some others that have more experience than me. I can share the triggers and actions documentation though.
https://wiki.keyboardmaestro.com/Triggers
https://wiki.keyboardmaestro.com/Actions
I'm not sure what the video stream browser page looks like but you might be able to use something like actions:Execute a JavaScript in Browser [Keyboard Maestro Wiki] to check the status of the stream on the page via JavaScript.
I also recommend checking out Tip: How Do I Get The Best Answer in the Shortest Time?