Add Nested dynamic pipelines

doc/ci/parent_child_pipelines.md

@@ -180,6 +180,9 @@ pipelines, which was later increased to two. A parent pipeline can trigger many
 pipelines, and these child pipelines can trigger their own child pipelines. It's not
 possible to trigger another level of child pipelines.
 
+<i class="fa fa-youtube-play youtube" aria-hidden="true"></i>
+For an overview, see [Nested Dynamic Pipelines](https://youtu.be/C5j3ju9je2M).
+
 ## Pass variables to a child pipeline
 
 You can [pass variables to a downstream pipeline](multi_project_pipelines.md#passing-variables-to-a-downstream-pipeline)