Fix video height not scaling down when browser window is narrow

This solution still makes sure the video doesn't jump in height
when it loads, and makes it so the video scales down properly in
aspect ratio as the browser window is made narrower.

youtube/watch.py

@@ -473,6 +473,7 @@ def get_watch_page(video_id=None):
         settings                = settings,
 
         video_height            = video_height,
+        video_width             = video_width,
         theater_video_target_width = theater_video_target_width,
 
         title       = info['title'],