I wanted to make a video demonstration of one software. I wanted to use text description instead of using voice description, a simple example of what I've explained could be this short screencasting, where author uses short text messages instead of explaining it with his own voice.

Could you recommend any free software for doing such a screencasting please? Would be better if it works in Ubuntu or if it is a web application.

UPDATE

I have found out Wink which could add explanations boxes as I said. Now the problem is that it doesn't support Linux 64bit, has only 32bit. Any other app like Wink for 64bit Linux?