I've been reading an excellent blog on SMARTboard resources by James Hollis called Teachers Love SMART Boards. Recently he posted on a really cool website that makes creating and embedding "mathcasts" very simple. What I really like about this particular post is that in addition to the finished mathcast, he has also posted a video that shows him creating the posted mathcast.
So check out his excellent blog, especially this post: http://smartboards.typepad.com/smartboard/2008/02/smart-board-a-1.html
and also the Sketchcast website.