How can I create a promotional video explaining "How to use my website"
a) It should show the screen movements of my cursor explaining different features of my website.
b) There should be a background voice explaining different features of website (I don't think my voice is good, can we have some generated voice)
Example something like this video (Here the voice is not so good):
http://startups.com/about Can some one help me to find if any such tools are available...
Camtasia Studio http://www.techsmith.com/camtasia.asp (appears to be the leader for this type of software. Ian Ozsvalds Screencasting Handbook at http://TheScreencastingHandbook.com is currently free. It will give you good tips on how to do this.
Instant demo http://www.instant-demo.com/ is another good choice. It is not free. It handles annotation and voice recording.
Wink from DebugMode http://www.debugmode.com/wink/. is very easy to use and free. It has annotation capability and voice recording.
Note for a professional video you need to hire a professional voice over person, unless your voice is exceptional.
Until now, everyone's answer has to do with creating a Screencast... That presumes you HAVE A PRODUCT already. The video you pointed to is a vector animation, which presumes you DO NOT HAVE a product. To build what you want you would need to hire someone or do it yourself, probably in After Effects or Flash.
In my experience the best solution for this is Adobe Captivate. Captivate efficiently creates full-motion recording when things are moving other than the mouse, or a slide with a mouse object/object path whenever it can.
This means that your published video is of a very significantly smaller size and thus it will load much faster for the end user.
Also, Captivate generates a lot of tool tips on the fly for training videos and can even be used for surveys/polls. It's a handy tool all around.
One of the easiest way to do (on a small to no budget). Record voice and put Flash animation based on sound-track.
Here's the great free tool for voice editing: http://audacity.sourceforge.net/ Unfortunately Flash is a commercial product. But there are some shareware options that will save in .flv format too.
CamStudio is freeware and certainly not bad. Look for someone with a better voice if yours isn't good enough.