I have reactivated a little piece of hardware I bought few years ago, called "NoteTaker". Using the included PC NotesTaker software, in conjunction with a screen capture tool, in the moment "Freez Screen Video Capture" and Windows Movie Maker (for effects), I can produce little videos, just by drawing. Showing these types of videos on a digital whiteboard, might be what I was looking for since a while. Or minimum it might be the starting point for evaluation of tools. One of my "quick and dirty" results can be seen on YouTube now.