A perfect example of why we all need to be extra careful when cameras are present. Australian aircraft registrations are just as searchable as the FAA's. The good news is that if there was an accident it never got reported to the ATSB.
I guess this goes in the "arguments against nosewheels" category...
That particular RV-4 looks like it has the shorter (original) landing gear legs.
Van's has since discontinued them and now sells a taller landing gear leg to give it better clearance.
The picture also looks like the gear are deflected down a bit from perhaps a porpoised landing or coming in with too much of a decent rate/angle and trying to wheel land it at the same time.
Hard to say exactly what is causing it. But the guy in the back does seem concerned. Maybe he's a CFI doing some dual instruction in it.
In my RV-4, I have the short gear legs and while it does give me better visablilty while taxiing around, it does give me less prop clearance. I find I prefer to 3 point the landings when an adult is in the back, and wheel land when solo most of the time. Also, I NEVER EVER touch the brakes until the tail is down and the stick is back.