code: function () {
      var self = this;
      var trackedControllerEls = this.el.querySelectorAll('[tracked-controls]');
      this.trackedControllerEls = {};
      trackedControllerEls.forEach(function setupController (trackedControllerEl) {
        if (!trackedControllerEl.id) {
          warn('Found a tracked controller entity without an ID. ' +
               'Provide an ID or this controller will not be recorded');
          return;
        }
        trackedControllerEl.setAttribute('motion-capture-recorder', {
          autoRecord: false,
          visibleStroke: false
        });
        self.trackedControllerEls[trackedControllerEl.id] = trackedControllerEl;
        if (self.isRecording) {
          trackedControllerEl.components['motion-capture-recorder'].startRecording();
        }
      });
    }
docs: Poll for tracked controllers.