Im using a Pi camera running on octoprint for my 3d printer. See my HA config below. Both URLs work if I paste them into a browser window. It does not require authentication. I notice when I add the camera into an entity card the icon it shows is a current snapshot of the camera view. But when I click on it to view the stream the window opens and it just spins and spins. Never opening the stream.
Also, if I insert the url in an iframe card it works.
I may have figured it out but maybe someone can confirm. I think the raspberry pi camera only streams in mjpeg and it looks like the stream component might only work with H264.