At EOR -13 seconds, one of the crew remarks "Runway in sight".
Which "could" lead one to believe that until then they were not visual.
Mind you they may well have been visual earlier and have run into some predawn ground fog and an associated inversion which projected the PAPI at a reduced angle. Review of the KBHM Met data shows that conditions were right, e.g. 92% relative humidity and little wind. Conditions above the rising ground to the North of 18 may well have been more conducive to such a mirage.