Wind Estimation in Multirotors - Finding EK3_DRAG_MCOEF

Hello!
I was referring the wind-speed estimation in multi-rotors tutorial by @Paul_Riseborough.
At around 37:00 he mentions the ground speed to be 8.8m/s.

I wanted to confirm how exactly did we obtained the value of 8.8 (For calculating the Airspeed)

My guess was that it is the gps speed of the rotor at the moment when it started to drift under the influence of the wind after releasing the pitch stick. So he just ignored the transient period and took the value of GPS speed at the moment when a stable x_acceleration was obtained. Is this correct? If not please rectify me.

Thanks.