As James noted, some modern browsers have begun blocking credentials in the format http://user:pass@resource, but if I remember correctly Blue Iris also accepts the username and password as query string parameters if ‘secure only’ is disabled in Options → Web Server.
http://resource/?user=user&pw=password
eg. http://192.168.1.10:81/mjpg/frontdoor?user=user&pw=password
My Blue Iris instance isn’t up at the moment, but perhaps you could try that. Here’s a few threads referencing the option:
After re-reading your post, I’m not sure I understand why you want to add the login and password into the URL though? It sounds like if you chose Non-LAN Authentication and the MJPEG stream is showing in your SharpTools dashboard, then you should be good now, right?
Or are you implying that you want to use an ‘external’ URL to Blue Iris so you can access your streams while away from home?