Neurological issues from an unexpected drug interaction, it's described in one of the video comments.
From the YouTube comment:
[The Pilot, Mr. Daryl Dyer, the owner - operator of the Fisher Celebrity, was an experienced pilot, aged 60, who was flying to the airshow.
He had been under treatment for a condition the nature of which I have not been able to ascertain, but it involved his being prescribed, and taking, at least two prescription medications. These two medications, it has been reported, can result in neurological issues. In addition, he had undergone a PET Scan two days earlier, and had been administered appx 1 litre of a mild radioactive fluid that acts as a tracer for the PET Scan. He came in for the landing, and, in his own words, " ....
when I was about ten feet from the ground, my brain shut down, it refused to make any more decisions, leaving me to be a passenger waiting for the crash......" He suffered only minor injuries, but his pilot's medical certificate was suspended for six months. He has since repaired the aircraft, and resumed flying it. In fact, in 2020, he replaced the somewhat problematic Rotec Radial with a Verner Scarlett Radial which has more reliability.]
I'm gobsmacked that he was able to recover his medical certificate (not to mention his pilot certificate) after admitting that he flew while taking multiple prescription medicines known to cause neurological issues, and that those issues (maybe?) led to a crash
at an airshow. According to Kathryn's, the plane actually bounced through the airport fence and finally crashed on a nearby road. The Australian authorities are certainly more forgiving than the FAA.