When watching this high altitude balloon video I stumbled across a weird thing: Go to 6:08 and watch as the black sky suddenly turns to blue due to a different camera position. This is an image from about 87,000 ft (26.5 km) altitude, and despite (or because of?) no longer looking towards the Sun the entire sky suddenly turns into blue for a moment. Usually, on such nearspace videos I observed the opposite: the black sky gets a bit blue around the Sun, that's obviously due to the light scattering by the very thin atmosphere when looking towards the Sun. But I haven't seen the opposite so far, except that I've seen somewhat contradictory videos concerning the sky color at the same altitude (which includes videos by ascending rocket onboard cameras).
Why does the otherwise black sky suddenly turn blue in the footage and what does the sky really look like around 87,000 ft to the human eye (I've never been to these altitudes myself)?