The point behind the idea using a Raspberry is that it's a fast switch between TV and secondary HDMI input, much faster then looking from the phone or tablet.
My idea was to use Raspberry pi3 and rtsp. I can use the same Raspberry pi3 at work and rtsp works nice and all. At home I can't get a connection for some reason. I'm guessing right now that I have some network issue, but what I have no idea right now. If I'm opening the rtsp link with username and password, then it just does not connect. When I use the link without name and password, then I get login window, but after filling the name and password, it doesn't connect anyways.