The video ESA video Progress launch timelapse seen from space is of course striking for many reasons.
However there is a strange, blinking light structure on Earth that's quite puzzling! I've added a GIF from two screen shots that I've cropped, shifted, zoomed and sharpened to highlight what I'm talking about.
It can't be a reflection from an ISS window because it remains fixed within all the other lights on the Earth. Look after
00:55 in the video, where it flashes at about 2 Hz.
What is it? Where is it?
According to the YouTube video's notes:
Timelapse of the Russian Progress MS-10 cargo spacecraft launched on 16 November 2018 at 18:14 GMT from Baikonur cosmodrome, Kazakhstan, taken by ESA astronaut Alexander Gerst from the International Space Station.
The spacecraft was launched atop a Soyuz rocket with 2564 kg of cargo and supplies. Flying at 28 800 km/h, 400 km high, the International Space Station requires regular supplies from Earth such as this Progress launch. Spacecraft are launched after the Space Station flies overhead so they catch up with the orbital outpost to dock, in this case two days later on 18 November 2018.
The images were taken from the European-built Cupola module with a camera set to take pictures at regular intervals. The pictures are then played quickly after each other at 8 to 16 times normal speed. The video shows around 15 minutes of the launch at normal speed.