I love Youtube. What I've used this tool for in the past is to check out my grandson's latest trick. My daughter in law downloads videos so the family can check out his progress.
For library use, I think we could use this tool anytime the library has something they want to share. Customers love the visual media and are always looking for a video to help them do things, we could incorporate this technology to demonstrate how to use the new catalog, how to get a library card, promotion for storytimes, moldi, just to name a few things. Have the access right on the website for customers.