This ProgrammableWeb Playground is a very basic example of how to query the YouTube Data API. The "Show Play List" button can only work if you input a legitimate API key (obtainable here). It is the first iteration of what will probably be a three-step iteration towards a more likely use-case. In this code-sample, we simply feed the API the ID# of a YouTube playlist that we happen to know about. We harvested the ID of that playlist from YouTube's public facing link for it. However, we'll be the first one's to acknowledge that this is not a practical use case. But it's enough to get your feet wet with a simple call to one of the YouTube Data API resources (the /playlistItems resource). This code also borrows from another ProgrammableWeb tutorial (and accompanying PlayPen) which demonstrates how to operationalize sample code that needs to hide any API keys from public view.
Click here to view the matching tutorial on ProgrammableWeb