Eh. The law is more likely to be voided based on the rulings mentioned in Indiana and Louisiana. The courts never seem to care about the eyeballing of required footage. Just ask all the folks who have paid fines based on distances for traffic tickets.
Plus, that whole 'beat the ticket, but not the ride' saying is too fucking true. It's shitty, but the legal system doesn't give a fuck. They've (the supreme court that is) even said that an officer pulling you over for a law that doesn't exist is perfectly fine.