If I'm home and TMR goes live, it asks me on my phone if I want to watch, and then starts it on my onn 4k pro.
Note that it uses the old deprecated https://github.com/custom-components/youtube. I'll try using the offical one but I think I saw that it required an api key.
It uses the https://github.com/home-assistant/core/blob/master/homeassistant/components/script/blueprints/confirmable_notification.yaml blueprint.