If you look at the You Tube page of the first video below the video are the comments and someone has asked the same question.
The Question (posted in the comments):
'' in the video, what do you mean by "now the REAL copilot istaking place"?? who was the guy who was sitting in copilot seat first? was it just a friend who is not a pilot? i hope not because he was doing the checklists
''
In response the author posted this;
'' Ha-haaa! I can imagine your precupation!
This guy the first guy belong officialy to the flightcrew,but was not yet a full "First officer" Here in Holland we call them a "Co-Co Pilot"!They are allowed to perform start-up with the Captain,taxiing,and doing radio;are licenced with simulator training,but not yet ready to perform takeoff and landings.The other guy,was the real co-pilot on that flight. and at that moment he had even the rating as a MD-82 Captain! Thanks for your precupation. ''
Aka.