Looking at the python code for the media_player.py component of the homeassistant cast module, it is clear that once a playlist is identified, only the first entry, playlist[0], is actually actioned.
From: https://github.com/trumpton/core/blob/dev/homeassistant/components/cast/media_player.py
| try: | |
| playlist = await parse_playlist(self.hass, media_id) | |
| _LOGGER.debug( | |
| "[%s %s] Playing item %s from playlist %s", | |
| self.entity_id, | |
| self._cast_info.friendly_name, | |
| playlist[0].url, | |
| media_id, | |
| ) | |
| media_id = playlist[0].url | |
| if title := playlist[0].title: | |
| extra = { | |
| **extra, | |
| "metadata": {"title": title}, | |
| } | |
| except PlaylistSupported as err: | |
| _LOGGER.debug( | |
| "[%s %s] Playlist %s is supported: %s", | |
| self.entity_id, | |
| self._cast_info.friendly_name, | |
| media_id, | |
| err, | |
| ) | |
| except PlaylistError as err: | |
| _LOGGER.warning( | |
| "[%s %s] Failed to parse playlist %s: %s", | |
| self.entity_id, | |
| self._cast_info.friendly_name, | |
| media_id, | |
| err, | |
| ) | |
