Some very interesting analysis of the in-cabin video, Simon.
As I noted a few posts back, the confusing factor is that the approach to the old airport looks quite similar to a circling approach to the new one if coming into 12. However, would you not agree that the onboard video shows them too high to be about to land into the old airport? It certainly seems that way to me.
Someone else posted the FlightRadar24 tracking of a recent flight for this same flight number that had indeed landed into 12 (but coming in from the south rather than north), so it does appear that the terrain further west demands this rather tight turn over the old airport into 12.