Power BI - Why do I need Power Query when I already have Power Pivot?

Hi, folks. At the WPC in July 2013, Microsoft announced the availability of Power BI - a comprehensive, cloud-first self-service BI offering. In addition to some well-known capabilities (namely Power Pivot and Power View), Microsoft adds two new "Power" offerings - Power Map (formerly known as GeoFlow) and Power Query (formerly known as Data Explorer). In this video, we make the case for *why* Power Query is such an important tool for use in conjunction with the rest of Power BI. For this illustration, we'll show how we can provide analytics against a "semi-structured" source of data - Craigslist.