What really makes this system workable is visible here.

         
right click above, select play

Below is a large video (9MB) at a screen resolution of 1900 x1200, showing me using the system to mark a student's work. It may take a while to load, depending on your broadband connection.

This is 6 lessons worth of work, so it takes much longer to mark than the work of a single lesson, which is the normal routine.

The video is a popup, and due to the dimensions, there is a visual lag at the end of this, but you can pause it to verify the content is there!

A senior moderator has checked the judgements I make in this video incidentally. Phew!