Jing
This piece of software captures what happens on the screen. With a microphone, you can record a description. A video is created and uploaded to Techsmith's own website. Provide the URL to students so that they can watch it.
Videos are stored online at http://www.screencast.com. Create your own folders to organise the Jing vids you create.
For more advanced features, you can pay for the full version. This is not necessary for standard teaching work. One of the features of the paid-for version is the use of your own video camera which means you can film yourself, for example. If you have a text that you want to record, you might like to use the free online tool Teleprompter.
On the right, there are links to three examples of Jing used in correcting some academic writing.