In a typical Udacity course, the hand written course videos are displayed with the writers hand beneath a semi-transparant view of the notes (1:02 in video linked below).
I want to replicate this to record some tutorial videos, but am stuck on how Udacity managed to achieve this effect.
Here is a video of their set up: http://blog.udacity.com/2013/06/coffee-break-episode-6-inside-recording.html
And here is some more information from one of the teachers: https://medium.com/teaching-learning/1d7c77b857de
From what I gather, they have a Tablet that they draw on, which they then use some form of screen capture software to record the video of the notes.
At the same time, they are recording a video of the teacher writing on the tablet.
With these two videos they seem to be chroma keying the screen capture out of the video of the teacher's hand.
How are they achieving this effect? If they are chroma keying the screen capture out of the teacher's hand video, how can this be achieved?