The bit they left out, was taking off with one wheel. Quite a feat, even in those days
I'm not sure about not having radios?
They would be below their service ceiling of 6500ft, for aerodynamic reasons. It's easier to achieve greater dynamic pressure/indicated airspeed and better control effectiveness. Helpful with someone on the wingtip.
At about 2:30 into the video, as Gladys is making her way toward the fuselage, along the trailing edge, aileron deflection can be seen reducing, as the pilot corrects for the imbalance in roll - in layman's terms.