Good question. I have seen it on many ask and answer sites. This was would be a problem for many beginners. Also, even some computer geeks would have demand to create software demonstrations to assist depicting their operations, but have no idea which software out there meets their needs. In this article you can get a proper solution for most condition.
Why record actions on screen?
Say you find some favorite videos and flash movies from web, or found a great software tricks and want to share with your friends, but do not know how to represent your actions on their screen. You play a game or find game tricks / secrets and want to show your play on web. You are trying to describe a computer problem to a technical friend or instructing software skills and you are trying to describe what you see on the screen: the operation sequence, the dialogs, the messages, the buttons whatever. You are not sure of the terms to use and your friend is having a difficult time understanding your description of what you see.
You must be desperate to own a tool that can help you represent what you see on screen. Screen recording tools can help you realize it.
Choose a tool wisely
To record video on your computer you need video recorder. Although most screen recording tools claim that they can record videos, or turn screen record videos, only software designed to record video can generate high quality videos (sometimes could be flash movies). Usually you get a really big output file (a 1 minute 640 * 480 resolution video clip is about 200MB). You need a video conversion tool to convert the AVI movie to a small one, for example MP4, WMV and so on. Some sophisticated screen recording tools can produce high quality and highly compressed videos (a 1 minute 692 * 368 video clip is about 10MB), for example, Applian Technologies Replay A / V and ZDsoft video recorder. I will write a review of video recording tools in later June.
Record actions on screen
This is different from recording video. You only record your actions on screen, such as mouse move and keystrokes. All most screen recording tools can make this. There are two recording approaches used by capture tools, one is capture specified frames per second, the other is capture only when you take actions on screen. The first method usually produces larger file size than the later one, but may keep more details, eg instant change with mouse over. Most demo creation tools implemented the second capture method, and some of them support both approaches. Many recording tools of this kind are called demo creation tool, they are designed to create software demonstrations, tutorials and simulations. The screenshots captured by those tools can be edited to create an instructional movie. You are allowed to add annotations and narrations to polish or strengthen your demos. Some can even create scenario based simulations, such as Adobe Captivate, Tanida DemoBuilder and Wondershare DemoCreator. What I want to highlight here is DemoCreator. It is a freshman in this field, but performs no bad than a sophisticated tool. I'm impressed by its intuitive interface and capture quality. Other tools can cope with this: Flash Demo Builder, ViewletBuilder, TurboDemo, Instant Demo, Flash (it's free), SWF Demo Maker.
Tools use the first capture method that can do this, but because playing game requires so much system resources that may cause the captured video laggy if the capture tool consumes much system resource either. So, I suggest tools designed to recording games, for example fraps, ZDSoft Game Recorder. Fraps provides game recording samples on its site,
Record PowerPoint presentation
General speaking, people using this kind of tools wants to convert PP presentation to flash movie for Web sharing or across OS playback. Although you may find PowerPoint to Flash tools on the Internet, they can not convert all effects in the original presentation. If you record presentation while playing, you keep every subtlety in the converted flash movie. The only deficiency is that you lose the link in it. Software convert PP presentation to flash movie by recording, Camtasia, ViewletCam, DemoCharge, Captivate. PP to flash conversion tool, Articulate Presenter, Wondershare PPT2Flash, FlashSpring. Robin wrote an article named, The PPT2Flash Top 20. You may refer it for more details, masternewmedia.org