Earlier quoted context omitted.
There's a better, longer video on Reddit. At the beginning of the video, it sounds like the Ram Air Turbine (RAT) is deployed, which would suggest a dual engine failure.
Dual engine failure with a stall right at the end as it's going in. Guessing it's either a foreign object ingested into both engines, probably a bird strike, or fuel starvation.
And here's a YouTube video showing a Ram Air Turbine (RAT) being deployed on a 787 for comparison: https://www.youtube.com/watch?v=oFBCGf50Trc&t=69s