The tools involved:
- Screencastle - web-based screencast tool. Doesn't get much much simpler - there's a big red button. Click it, record, and it'll give you a bunch of URLs to use.
- Greenshot: Open Source (Windows) screen shot capture tool. Also very simple - capture, and immediately get a simple editor in which to mark up your capture.
- Jing - free (windows or mac) screencast OR screenshot tool, so it kind of obviates the other two, but maybe one of them just works better for you.
And here's the Screencastle output: