What are good instructional cooking TV shows?
Good Eats (Food Network): Explains some of the science behind why techniques work, and occassional information about the history of the ingredients or dishes.
America's Test Kitchen (PBS) and Cook's Country (PBS): Explain the techniques that they've used to improve dishes, and have occassional segments explain the science behind cooking processes.
Mexico - One Plate at a Time (PBS): Describes the differences in the regional differences of mexican cooking, and often compares historical versions of dishes to the modern versions.
Deep Fried, Live! (web animation): Flash animation cooking show that allows you to click at various points to get more information about ingredients &amp; techniques.
In Search of Perfection (BBC 2): Heston Blumenthal brings his molecular gastronomy techniques to some of Britains favourite dishes such as roast chicken, fish and chips, spaghetti Bolognese etc. The show was followed up by a second series, "Further Adventures In Search of Perfection".  At the time of writing, episodes from both series can be found on YouTube.