The Instagram video linked in the article looks like he is drawing from the watch sitting on the table. No photograph is visible. That might be intentional though...
A grid is visible in the background of the drawing. Such a grid is used to set up the initial outlines, by copying it from the reference photo with a grid drawn on top of it (typically done in Photoshop). Other artists use a projector to trace.
As another commenter mentioned, the depth of field removes any doubt that a photo is used as a reference.
Picking up and placing back the watch to see details would constantly change the lighting, especially in the details. It is impossible to get such a level of detail by "drawing from nature", even in studio conditions.
It's not a coincidence that paintings only became more realistic after the invention of photography.