It is a technical reconstruction of the flight path, by starting with a cctv footage, then manually stablising it and obtaining key frames from it. then starting with a simulation model, and setting it up to match the key frames, they find a reconstructed path. with this, thy can comment on the time when engines lost fuel, when exactly did drag take over, and also find mistakes in the prelimnary (official) document submitted for the accident. They also share their model and data, and explain the sequence of events.