Hi Craig - thanks for your video contribution! It's a tough question, but since I was the one that posed it to you I feel I owe you a reply in return...
If I had to pick one e-learning interaction, it'd be a myth/reality (or true/false) exercise. Essentially, it's a drag-and-drop which can be dressed up in different ways visually and in terms of the category labels. I like these activities because they can be a great way to engage people and to challenge attitudes and preconceptions - I often include them at the start of a course, to show people that perhaps they don't already know everything about a topic (especially useful with compliance) or that there are grey areas between the black and white extremes, for example.
(One of my former colleagues, Jennifer Wrigley, wrote about this kind of interaction on the Spicy Learning Blog last year, as it's her favourite interaction too: http://www.saffroninteractive.com/whats-your-favourite-e-learning-interaction/)
Thanks again for contributing to our video library!