my_use_case.yaml

mpd:
- manifest_edit.plugins.mpd.descriptor_add:
    periods:
      - '*' : '.*'
        adaptationSets:
          - contentType: "video"
            representations:
              - '*' : '.*'
                plugin_config:
                  name: 'SupplementalProperty'
                  schemeIdUri: "MyCustomName"
                  value: "MyCustomValue"