Google Cast?

On the screenshot for vertical player, there's a chromecast icon. However, I can't seem to find this vertical view, or the cast button.

Start by comparing the referenced vertical-player screenshot with the current player UI and locating the existing player entry points. Determine whether the requested work is to restore the vertical view, add Google Cast support, or both; done means the intended view and cast button are available as described.

Written by the indexing model from the issue text.