Choose A Different Ending

"Choose A Different Ending," produced by AMV BBDO in the UK and deployed for the Metropolitan Police in London in 2009, was a "Choose Your Own Adventure" (CYOA)-type experience where one video links to another. It was a great implementation of YouTube's Annotations product. Annotations only work within YouTube, and Interactive XML adds a lot more power to them with features such as "memory" within an interactive session and between sessions, looping, calculations, variables, http linkage with other services, etc. It's like Annotations on steroids.