From Kadee couplings and large tension locks to Fleischmann hooks and proprietary couplings used on the Virgin Pendolino, this video takes a look at them all. And helps us all to never get confused about these small but essental bits of the hobby.
Image of woman at 2:20 - 'Curvaceous Crystal' by Tim Lucas (Flikr username: toolmantim), http://www.flickr.com/photos/toolmantim/2161618741/in/photostream/, used under the Creative Commons Attribution 2.0 General License, details available at http://creativecommons.org/licenses/by/2.0/deed.en_GB