You could subpoena the police department for the video or FOIL request. However, if you were charged with talking on the phone, it is unlikely the police camera will have much of the footage. It would be more useful to obtain the call records from your provider. This way, you could actually show that you were not on the phone at the time you were pulled over. However, you would need to cross-examine the officer and use such records as a form of impeachment.
Finally, you should also be aware that if you were charged with using a portable electronic device, then the prosecution need only show you were “using” the device. As a result, phone records would not completely get you off the hook.