Sorry. It is a browser extension. My boss wants a few people to have access to the live streams when away from the office. I am trying to figure out if you can do that through a browser extension and have Blue Iris recording at the same time.
No need to have a browser extension, BI comes with an amazing web server / remote viewing system made by @bp2008 called UI3. Click on settings, then Web server to configure
You will have to either set up port forwarding or a VPN to view remotely. I blocked out my IP for security reasons.
x3 on seeing if the BI web server meets your requirements. To your original question, as long as your cameras can support multiple simultaneous streams, they should be able to stream to BI and someone connecting via the way ya'll have be doing it.
For future viewers, that is not advisable to use upnp, just the opposite, make sure all instances of of UPNP is disabled.
Use a VPN: VPN Primer for Noobs