I just completed the training for SCRUM Product Owner with Agile Learning Labs. Chris Sims was a very good instructor. He explained the what, the how, and the why of a Product Owner (PO), as well as the PO’s responsibilities to the stakeholders and to the development team. Successful PO needs to regularly prioritize user stories relative to the potentially changing requirements and valuation of the stories from the stakeholders. At the same time, the PO needs to fit an appropriate number of stories, by story points, relative to the capacity of each sprint. Asides from various exercises, the training included a half-day simulation that ran thru 4 sprints. That helped me understand what really is needed and expected from the product owner in the SCRUM process.
Chris also showed a video from Henrik Kniberg that illustrates the process of SCRUM from the perspective of a product owner. I found this video succinctly explains the process of SCRUM as well: