I don't know what the laws are like there, but here in the US if it's a criminal court then the burden of proof is on the prosecutor, and the goal of the defendant is to build up a doubt "beyond a reasonable doubt" in the eyes of the judge and/or jury.

If the driver is on trial for a crime, the burden of proof that any evidence against him is not tampered with is on the prosecutor, not him. (That said, it doesn't have to be proven, only shown.)

If it's a civil case, the burden of proof is a "preponderance of evidence", which basically means "which is more likely? If one seems 51% likely and the other 49%, the former is what wins". So the burden of proof for things would be on those who bring them up.

Simply saying "it could have been tampered with" without any evidence should not be very convincing, but every little bit of doubt might help, especially with a jury rather than a judge.

That said, courts have rules on the type of evidence they will accept, and certain types of evidence can be dismissed out of hand, not even allowed to be brought up. And it's entirely possible that some courts could so rule about photo or video evidence, especially when tampering by anybody but the police could have been done.

Photo and video evidence is highly convincing to a jury, but in some cases it's very easy to forge. So I can certainly see where it could be prohibited in some cases, especially minor cases where the resources to properly authenticate it won't be made available.