Runway overrun.
Determining the TD point is a very simple matter but the above graphic is indeed incorrect. The actual TD point was much further along with even less runway remaining.
Google Earth is detailed enough at that location to get very good ground references also visible in the video. You can clearly follow along as each reference landmark passes the camera and the jolt of touchdown is easily noted.
The above graphic has the TD point after approximately 1000m of runway was used up with about 1,400m remaining to stop.
The actual TD point, determined by video reference to overhead imagery...
was after about 1,470m with only 950m remaining.
You can clearly see the closed Taxiway (the above supposed TD point) go past in the video, followed by the RNY crossing itself The actual TD takes place beyond the RNY crossing point about the point abreast of some airport field equipment seen near the service road.
Hope that answers the question of HOW the touch down point can be determined even though the above graphic is incorrect.