I teach mostly "English Listening" classes that focus nearly solely on listening (at a Foreign Language High-school).
Could you guys share any video clips that you have that have have clear dialog in them? It seems like most video clips that are posted are songs or silly things for entertainment and lacking.
They can have one or more speakers, but it's best to not have a lot of distortion or background noise.
Here's one of the better clips I've been able to find: The Incredibles' family:
http://www.youtube.com/watch?v=3v196bt5kTUAnd here's one I used for my advanced class:
http://www.youtube.com/watch?v=ohU16OiduUsCheers