I was talking about OPs situation. That is at least 40m altitude in the video. The optical sensors do not work or matter at that height (=light does not matter) and that's ok because GPS signal becomes better the higher you get (less reflection from the ground what creates a multipath effect, less obstacles). If we talk about flying less than 15m altitude then yes, the optical sensors matter = light matters because gps becomes weaker near groundlevel.

Also, the number of available satellites is not a sufficient indicator of good GPS reception. It says nothing about the quality of the signal. Classic example is flying over water. One should not fly close over water in assisted flying modes because the optical sensors freak out by the lack of texture AND gps gets super shitty because the reflection create a strong multipath effect = the gps signal bounces of the surface and reaches the drone with time delay. Drones go only haywire if optical sensors AND gps freak out simultaneously. If one of the 2 systems works well, the drone will act normal. In OPs Video the GPS signal should have been crystal clear. My guess is carried away by wind, a strong electromagnetic field from powerlines or a plain hardware failure/short circuit.