Would that be an issue if only used on a local network with limited access? Maybe I'm missing something...
Sorry, here's a better link format for VLC so you aren't prompted for login info everytime. ”rtsp://username:password@address/h264Preview_01_main”
***Not tested, just an ideal***
If you're using IP cameras you might try installing the VLC app on your Firestick and opening the stream to your camera. I can do it on a PC (going through my NVR) by selecting ”Media” -> ”Open Network Stream” -> Entering the link info ”rtsp://[IP Address of your NVR]/h264Preview_01_sub” (01_sub = Camera 1). Hope this helps!