I've seen parts of the video and the first thing that made me wonder is that these lights move like locked to each other. They have no velocity relative to each other, for quite a long time, but move together.

That reminds the famous Capitol/capital UFOs detected over Washington in 1952 (also 11 in some reports). Later it had been detected that these lights mirrored the formation of street lights down on the ground.

Under certain weather conditions (temperature inversion weather) pockets of warm air can lead to signals detectable by radar, but not by the eye.

Listing possibilities is not an explanation yet, but I'd start with looking at the weather conditions at the time of the sighting (in March) and would look for earthly sources of light mirroring the stable pattern of celestial lights.

Wolfgang