We've seen that at the boat ramp before. Guy pulls his 20+ foot boat up the ramp with a small 2 wheel drive s-10 pickup. Has to really give the little truck a kick in the pants to get going and the boat slides right back off the trailer and onto the skeg of the outdrive. Must have forgotten to lock the winch or hook up the safety chain on the bow eye.....was a roller trailer to make thing worse.