Since I saw the original Airline film crew a few times, I'm sure the rules were the same back then. But provided that you have checked in online, the 10 minutes is mostly theoretical. Boarding is rarely completed 10 minutes before departure, and until it is completed the Ops Agent and Gate Agent have no idea whether or not you are in the boarding line. The real cutoff is completion of boarding, at which time the no-shows will be deleted one by one, presumably starting from the bottom of the list (latest check-in).
Where the 10 minutes truly applies is when you did not check in online or at the airport or if you were unable to get a boarding pass due to the maximum number of pre-issued boarding numbers having been reached. If that happens you will lose your confirmed status at T-10 and become a standby passenger.