The video linked walks you through setting up a blocking task for the "Instantiate vApp from Template" operation. When logged in as a System administrator, you are able to place a check in a box to enable one or more of the many available blocking tasks. Please refer to that video and the package as guides to get you started with blocking tasks.
The act of actually triggering a blocking task is, for example, trying to deploy vAppTemplate from catalog - Add from Catalog in MyCloud area.. This activity, as demoed in the referenced material above, triggers that particular blocking task. Depending on the activity you wish to have a workflow triggered, you will have to enable various blocking tasks. Check under Administration -> System Settings -> Blocking Tasks to see what kind of blocking tasks are available. And be sure to review all the material that I and Igor have linked to.
If you have not yet setup an AMQP server, I recommend checking out Mike's post here: http://www.mikedipetrillo.com/
