Mid summer in Texas. Dry downburst? Developing dust devil? Either could be forming mid field just as they started take-off roll. A sudden headwind increase as the tail is just about to lift could conceivably have the aircraft prematurely airborne. Then all it would take is a shift in wind direction or intensity to do the rest.
I still hesitate to say 'pilot error'. Looks to me like they did abort as soon as the control difficulty became apparent.
Knowing the (not) recommended short field method for this old bird, it does not look to me like they were attempting anything so risky. Those good ol' boys spend a lot of time and money restoring these lovely machines, so I doubt that they then put them at risk.