ReplayNote is an app that records your writing and voice, then converts it to YouTube video. (screencast)
You can create a video and share it just by clicking a few buttons. 
It is quite easy to create educational videos using ReplayNote. Or you can record meetings, or you can ask questions or explain something which cannot be easily expressed with text.
The interface is very intuitive, so just try a few minutes to get used to ReplayNote.