CamStudio is an open source screencast application cabable of capturing both audio and video directly of your PC screen - and store it for later playback. This is great for demonstrating how different applications, websites, etc. work and how to use their features. CamStudio outputs AVI files but is able to convert these to macromedia flash files (swf), so that the screencasts can easily be used on any website. Advanced features include adding of captions, video-in-video e.g. for narrator and CamStudio's own loss-less codec, which provide sharp images while keeping the filesize to a minimum
