Not necessarily. Hypothetically, if the peeps took the GoPro cams before the cops showed up and locked them in either the glove compartment, or the front trunk, then I do not believe the police would have right to search those, not if they were pulled over for stunting. I mean, sure they could unlock those and view the GoPro footage, but I doubt it would be admissible in Court.
Again you are incorrect in your assumptions. The cars are now impounded, as part of the impound process the car is "inventoried" to ensure the owner doesn't later come back and say, "I had a $10,000 diamond necklace in my car which is now gone." If a camera was discovered during the inventory process, it would be seized, (but not viewed), until a search warrant was obtained at which point anything on it would be completely admissible.
As Brian P correctly stated, NO ONE knows what evidence may or may not have been obtained, including the defense lawyer. At this point the lawyer is merely going on what his client(s), have told him, and as well all know NO one ever lies to their lawyer..lol.
I agree 100% the s172 legislation imposes unfair and punitive burdens upon the accused. I too wish it had never been enacted, but it was and the courts have ruled on it so that boat has sailed, our whining about it won't change the fact, of it's far reaching consequences.
Just like anyone who is charged these people will have their day in court. BUT, again it shows the importance of ONLY having your GoPro rolling when your behaving, and in order to protect yourself, in the event of an incident in which you are 100% not liable, either legally nor morally. My GoPro's saved me when another driver who had sideswiped my bike tried to have his insurance find me 100% at fault for the damage. After reviewing the video or BOTH cameras, my insurer, advised his company they were holding him 100% at fault, for the collision. But I always rode, responsibly, so I never had an issue, had the GoPros been seized. They also NEVER were positioned so as to provide a view of the speedometer, etc.