casttube provides a way to interact with the Youtube Chromecast api.
Install:
pip install casttube
Features
from casttube import YouTubeSession
session = YouTubeSession(screen_id)
# YouTube video id is http://youtube.com/watch?v=video_id
session.play_video(video_id)
The library requires 2 things:
There is a small script in https://github.com/ur1katz/CastTube-Scripts to print the screen id and launch the app.