Are there any browser-based technologies or protocols used by YouTube that enable this functionality without relying on a server intermediary? When i try to cast from Chrome, it only display the ChromeCast device as available. I imagine that the YouTube App that is installed on FireTV acts as a custom receiver, but how can the website discovers it without access to my local network directly? (as i can do with nodejs ssdp).
I've explored DIAL, SSDP, and server-based approaches for device discovery in the local network. However, I'm specifically looking for insights into how YouTube's website achieves device discovery and casting to devices like Fire TV Stick directly from a web browser.