Here's a little demonstration application I recently put together using a combination of Flex, Swiz, Degrafa and the YouTube API.
You can see the application and view/download the source here: http://www.davespanton.com/demo/TubeDemo.html
It uses a presentation model pattern to decouple the views from the rest off the application and Swiz to manage dependency injection and event handling.
The rest of the application speaks for itself, so feel free to dig in and have a look.
UPDATE : Due to changes in the youtube API the demo no longer works as it once did.