Hi Jack, I would be surprised if it was leaking from the point you indicated as any water leaking from there would run down the door seal lip.
If the water is right on the edge of the floor mat you should see a drip mark on the plastic trim covering the door check, you may find the leak point is actually the sharp crease in the door seal just below the point indicated.
Or as has been pointed out it is the vent flap seals that are leaking, the foam seals are not very good esp after 10yrs.
I have replaced mine with S3 rubber seals and through all the rain in the last few months the floor has been bone dry.
Try replacing the vent flap seals its the cheapest fix first, it's 2 fiddley M6 bolts and 2 pins use plenty of WD40 to remove the old seals from the flaps as it will cleanly remove the adhesive.