Video capture tools allow you to record your movements on a computer, with audio, to demonstrate to others how they can use computer applications. Recording a presentation is very helpful, especially when you want to play the presentation for a group while assisting your audience, if you have to give repeated presentations to multiple classes, or if you want to imbed the presentation in a wiki or website for others to view at their leisure. Here are two free downloads that allow video capture:

Screencast-o-matic http://www.screencast-o-matic.com/ The "original" online screen recorder for MAC, Windows, or Linux. No download required. You can record without an account, but hosting on the site requires an account. Video length is 15 minutes. And remember...it's free!!!

Camstudio http://camstudio.org/
Capture a demonstration on your PC computer screen, and add audio. This free tool is great for preparing video tutorials which can then be imported into presentations or embedded on a website. Make sure you also download the optional MP3 encoder so your videos will play in Microsoft Media Player. Free, but only available for Windows.

Screenr http://www.screenr.com/ Similar to Screencast-o-matic (free, cross-platform, easy to use) but maximum recording time is 5 minutes. This tool is valuable if you're looking for very concise video presentations.

Screenjelly http://www.screenjelly.com This has a three-minute limit, but it's really easy to record your screen activity and your voice, so it makes the top of this list.

Jing http://jingproject.com
Jing is similar to Camstudio, but claims it is easier for students (and teachers) to use. Available for Windows or MAC.

Skitch http://skitch.com/
Save a screen shot of an image on your computer, then add text, arrows, etc. You can then import or imbed your image in email or on a website.

Aviary http://aviary.com
Video capture, photo editing, logos, web templates, filters, color palettes, and more...on the "fly"!