Sometimes doing something leads to doing nothing. Francis Alys

How important the role of documentation is to a piece?

Are the roles of performance and documentation both equal in the piece?
Does the work shift from the act/performance of a piece, to the work as video documentation due to the transient nature of the act?

Would the viewer see the piece differently , just walking past on the street to seeing it as a video? would the viewer even know it was art?