While looking for interesting things to show I found quite a few interesting videos. Unfortunately almost all of them were way too long. I ended up with a video about C# 4.0 and the Dynamic Language Runtime (DLR). If I had watched the video before showing it I would have noticed that it lacked any kind of demonstrations, but in the end I found it interesting.

C# 4.0 Dynamic with Chris Burrows and Sam Ng

Here are a few links to browse through if interested, and of course, searching for "C# DLR" in your favorite search provider will provide you with lots of more information and samples.
Dynamic Language Runtime Overview
Using Type dynamic (C# Programming Guide)
CodePlex Page for Dynamic Language Runtime