Taxonomy is a very powerful classification system, so powerful in fact that it's hard (and resource intensive) to fully utilize it in Views and other queries.
Given a list of videos tagged with a specific vocabulary, I wanted to show a view of these videos on the page of another node type (a "channel") that is also tagged with the same vocabulary. The idea is to create video channels that implicitly relate to videos by sharing taxonomy terms, instead of explicitly relating the videos to their channel (using node references for example). The videos should show on the channel's node page.
The taxonomy system is one of the great contributions of Drupal to the technology of CMS: the ability to classify content with multiple vocabularies. Each vocabulary represents a dimension of concern in the content being managed. Further, a single taxonomy has a flexible structure: it can be linear, tree-like, even graph-like when multiple parents are chosen. Content can be restricted to be tagged with a single term, or multiple terms can be allowed. Finally, freetagging is supported.