Hi John,
That's just the marketing people showing off in most cases.
It's good practice to keep the belts of unoccupied seats fastened during flights though, as many an embarassed helo driver has ended a sortie with severe damage to the paintwork caused by a loose belt flapping in the breeze. There is another thread discussing the merits of leaving the controls with the rotor turning to secure a seatbelt - it's an old helo driver problem.
You're not supposed to leave the controls so you can't ensure that all the belts are in and doors locked during a quick changeover. On the older Bell 206 and 206L models this is a common occurrence as the door can look closed but the latch doesn't engage properly and the door opens in flight, loose seat belts fly out and the damage is done.
Hope that answers the question.
Cheers
