Do you have a source for that?
Police use video evidence at courts all the time; recorded interviews with suspects, cctv footage from street cameras, and from their own body-mounted cameras.
And what do you mean by raw footage? Isn't raw footage what's expected as opposed to anything that has been manipulated or enhanced in some way?
Video footage can not just be taken from a camera and then used in court, it must first be verified and then processed for court use. Only once footage has been verified can it be used in court as evidence.
Raw footage - original copy
Verified footage - evidence
The courts may require a Traffic Officer to describe what he see's happening in the video footage for it to be used in a case.
My source is several police officers in the met, some who deal regularly with video from patrol cars, others who deal regularly with verifying footage for use in courts.
Video can be manipulated and you can make footage show only that what you want to show. As such it is not technically as strong as an independent witness.