Resources for how to capture audio from multiple browser tabs?

I'm looking for resources about how to capture audio from multiple browser tabs simultaneously.

So far I have only been able to find stuff about using browser plug-ins that would require user intervention. I would want it to systematically capture 5 minutes or so, then start the next capture automatically.

If there's not an easier way to do this, then maybe I can look into making a plug-in. But I'm really hoping there's some other way. Thanks in advance for any suggestions.