interesting discussion...
there is a duty to disclose all evidence to the defendant
this was publicized in the Commission into the wrongful prosecution of Guy Paul Morin
of course it was DNA evidence that acquitted him
but the report was very critical of Durham Police for squashing evidence that would have benefited the defendant
But, as has already been stated, video that may or may not exist on a cell phone is not "evidence" unless it is actually entered as such in court.
In the situation above, evidence that comes to light after the trial has to be brought in following proper procedures in the courtroom.
If the original poster wanted to make use of what may or may not have been on that video then it should have been brought into evidence way back before the first trial. It should have been requested, and the process should have been followed BACK THEN. Now, as mentioned, there are plenty of reasons why that video may not exist, or its existence can be legitimately denied, or could be declared inadmissible, or who knows what.
Besides, there is a fair chance that even if that video did turn up, what it shows might not necessarily be in the original poster's interest. Unless it shows that the original poster was fully in compliance with all applicable laws including never exceeding the speed limit, it's probably not in the original poster's interest. If the original poster was fully in compliance with all applicable laws, there wouldn't have been motivation for the officer to pull the rider over in the first place. Yeah, sure, the cops can make random stops, they don't need probable cause, this is Canada, not USA. But such stops generally don't involve forcibly separating people from their vehicles. Just my opinion - We haven't heard the whole story here ...