Mick,
It never free fell, in the technical sense, as it was suffering drag throughout.
A free-fall parachutist is also only briefly in physical (rather than semantic) free fall as they leave the aircraft door; as soon as drag builds, the weightless and acceleration go.
Vomit comets also don't free fall, they are flown precisely so that thrust balances drag so the zero g is imposed by the aerodynamic forces.
The test of the free-falliness of a gopro is that a real dragless free fall covers a height that's the square of time spent falling, while at a terminal velocity it's a linear relationship. 120s from 12000 feet, 100s from 10500 feet, 22s from 2000 feet and 27s from 3000 feet, are all consistent to within 10% of a 100 ft/s terminal velocity being quickly attained.
The freefall time from 35000ft is indeed about 45s, without air, or for an object so dense/streamlined that it doesn't suffer from any effective air resistance.
In contrast, dust and smoke floats, and never makes it the ground.