You can actually detect this. Chess.com detects things like this for cheating chess players. The idea is that people who are cheating at chess with a computer h

You can actually detect this. Chess.com detects things like this for cheating chess players. The idea is that people who are cheating at chess with a computer have several identifying characteristics even if you ignore the moves. Things like the time spent per move, switching to a different window or tab, etc. You could probably do something similar with recorded sessions like what GP suggested. Even someone doing what you suggested could leave behind a distinct profile in the shape of the session.