Player.md - is there something like getTime() or isEnded() ? Would be nice with list of functions available that can be accessed with JS

Since the old player was removed from Twitch’s API documentation and is now unsupported, it might be broken. Twitch only offers their new HTML5 iframe player, which does not yet have a public API. To get notification when the channel goes online or offline, you may need to resort to polling Twitch’s API.