If you've come up with a really cool screencast, hosting it would be a bit of a problem. Most video hosting services such as YouTube (the video upload feature on Blogger is, currently, very YouTube-like) limit the size of the video thus reducing the clarity, often making text unreadable.
However, there are services such as Vimeo and Screencast.com that are just perfect for sharing screencasts. They support much larger sizes for videos and are free to use. (Screencast.com limits you to 2GB of storage and 2GB of bandwidth for their free services)