Using CaptureDevice/DirectShow for input Media and Chromecast for output Renderer is not working - confirm bad or help

[merwinsson]

Using VLC 3.0.3 64 bit on Windows 10 1803.
I set the Playback Renderer to my Chromecast, then I Open Media using DirectShow and select my WebCam video and audio.
After a warning about a necessary audio/video conversion using a lot of power and my giving the go ahead, the Chomecast screen goes dark and says "dshow://" plus a spinny circle thing and a time index that never changes from "00:00" at the bottom of the screen. That's all I get, forever.
Now, if I change the Playback Renderer to Windows, I see the Webcam output on my monitor and also hear what I'm saying into the Webcam on the monitor speakers (with some reverb of course due to feedback). So that works.
Also, if I change the Playback Renderer back to my Chromecast, and then Open Media using an audio (mp3) or video (mp4) file, my Chromcast plays it happily (although the mp4 studders heavily). So these work.
So it seems setting your Media to CaptureDevice/DirectShow and your Playback Renderer to a Chromecast is busted.
Can someone confirm, or tell me what I'm doing wrong.
Also, my REAL goal is to use CaptureDevice/DirectShow with NO VIDEO source and and AUDIO source set to my Headset Microphone while setting the Playback Renderer to the Chromcast Audio in my son's room and blast "WAKE UP YOU DORK" over the speaker attached to his room's Chromecast Audio. This does not work either. But playing a file to it does. So right now I blast classical music (which he hates) and that gets the boy up. But the potential for using VLC to make all my Chromecast Audios into loudspeakers is just too good of a thing to pass up trying to get working. I can think of quite a few useful applications besides the one I've described.
I think Google DOES NOT WANT this at all, as I searched 4 hours on the Play Store looking for an Android app that casts your phone mic to a Chromecast, and was not able to find anything. Hell, Google Chromecast tech support doesn't even like you casting ANY LOCAL content to the device at all. They seems to think the device is to be used exclusively to cast audio from apps on your phone that pull content from the cloud. They don't want anyone to get clever and use it beyond that. If I can get VLC to do my bidding, I can foil their evil plans.

[buggo]

What I ended up doing (but it is an ugly workaround),

1. Stream my microphone from vlc on say :8080/mic.mp3
2. Open the url in chrome and cast it from there

This however generates a slight delay (~6 seconds for me) which is I guess due to buffering and other latency aspects of the streaming server.