You can try https://commondatastorage.googleapis.com/gtv-videos-bucket/s... (I took this from a Flutter library used by my app). I'm curious to know if your TV can play the video.

I guess that's what separates side projects from "professional" apps :D They can have the same functionalities, but the professional ones are more polished down to the minor details. Mine: copy-paste URL. Theirs: video file upload or integration with Google Drive/Dropbox. Behind the scenes, they both use a URL. But my app will get there!