reconstruction drawing sequence from video
This is more a Computer vision question I think.
I don't know how exactly you can achieve that but some ideas and keywords you may use to find additional resources:

Feature tracking of hand and pen can yield the movement of said things. Assuming you know that the camera is not moving I think that would give you good results. Related is maybe motion tracking. Any information you have about the hand and the camera can in some way be used to make more accurate estimates.

Removing the hand from the video could be much harder. I don't remember that part from my lecture. We copied parts of the image onto the part we want to remove and used image metrics to make sure it fits best possible... But since the hand covers a drawing we don't know much about this could be very hard to do in an convincing way.