They would need an accurate reading of your speed, people think police can just use their eyes and detect your speed and report you and take it to court even though sometimes they do that as judges nowadays just believe a coppers word even without evidence, unless you went through speed cams or the vehicles were fitted with speed enforcement systems then its very unlikely they'll bother reporting you, also hate to break it to people but their dashcams only record their speed, road they're on, if lights are activated etc, they do not record a vehicles speed..they can obviously see someone fly past them which doesn't look good but in no way can they accurately tell your speed and this "between two point" isn't an accurate way of judging speed it just supports the officers professional opinion of your speed he seen with his eyes, same with dashcams all they do is support the officers opinion that you were speeding. Not to mention if the officers get your speed on a calibrated speedometer and decide to not pull you and carry on dealing with other things they cannot come back to that and use that agaisn't you as the accuracy would be void, however if they get you with a radar gun then its a whole different thing.
Also, don't speed...it will catch up with you eventually and think speeding is the most pointless thing and hope the police do catch all speeders but i don't agree with just taking a coppers word without evidence which seems to be happening an awful lot nowadays and know someone who went court and got found guilty based purely on the officers word and he had no reading of his speed etc, i'm assuming this was in the UK.