This video gives a good explanation of using and positioning widgets. However, the Theme used is the default prior to WordPress 3.0. It only allowed for one widgetized area. That is why the narrator talks about Widgets in the sidebar. As you now know, the 2010 Theme allows six widgetized areas, two in the sidebar and four in the footer area. Themes may offer fewer or more Widget areas.
Also 2010 offers many more Widgets than this Theme in the video.
The one thing not covered in the video is using the same widget in multiple widgetized area. There is an application for this but you probably will not want to duplicate most widgets in separate areas. This applies to categories, tags, calendar, etc. However, for general Widgets that allow customization you may. These include Widgets included in 2010 (varies per Theme) such as “Text,” “Image” and “Custom Menu”.