The only snag is if you want the evidence, you have to get it BECAUSE you're going to court, you can't just have it for no reason.
....Then can't you proceed as if going to court, check the evidence, and : -
1) - If the video shows clearly you are at fault, write to the court pleading guilty and not wishing to waste the court's time, but explaining that you were in doubt and therefore needed to see the evidence as you feel it is your right to do so. This would all be done before any date of hearing was reached.
Unfortunately, by this time, the CPS have already worked on the case (the CPS have no involvements if a FPN is accepted and payed), and can still claim their costs. I would, however, hope most magistrates are reasonable and actually deny any costs, providing a guilty plea is entered at the earliest opportunity after the video evidence was made available.
Another problem, if the CPS only disclose the evidence 7 days before the Court hearing, the defendent is effectively commited to turning up in Court in person, thereby not only wasting his own time, but it will mean that a CPS lawyer will also be in the courtroom to present the charge and an outline of the evidence - again, adding to potential costs against the defendent - which wouldn't have occured if they had seen the vid at the roadside.
Whilst the British legal system is supposed to be one of the best, it still does have some pitfalls too.
