core/homeassistant/components/media_player/strings.json

{
  "device_automation": {
    "condition_type": {
      "is_on": "{entity_name} is on",
      "is_off": "{entity_name} is off",
      "is_idle": "{entity_name} is idle",
      "is_paused": "{entity_name} is paused",
      "is_playing": "{entity_name} is playing"
    }
  }
}