The prius had its own problems different from the acceleration problem found on the 10 recalled toyotas.
The Priuses (and all hybrids, but most to a lesser extent) have very complicated braking systems. Pretty much as soon as you let off the gas, the computer gathers the energy of the spinning wheels to help recharge the battery. This happens during braking and not. The system gathers data very quickly, probably a thousand times a second (1KHz) and quick changes can affect it. The prius had a problem where (if i remember all the issues) on bumpy roads while turning and braking the brakes would take about 1 second to respond (as opposed to instantaneous braking). That 1 second could turn into about 60 feet on the highway, which is a BFD. This is an issue with the electronics of the complex braking system, not the accelerator.
On the other hand, that guy who went 90+mph was just trying to get his 15 min of fame. He faked an accel problem, while priuses havent had them