I was surfing YouTube and found a fair number of videos of cyclists and motorists who taped their arguments with law enforcement officers over traffic violations or similar matters. This tactic never works and usually results in the officer citing you for every infraction and count he/she can think of.
If you don't think a law is fair, that isn't the officer's problem, it is the law and it is his duty to enforce it. Even if you think the officer is in the wrong, remain calm and civil. Most of the time an officer has some discretion in writing tickets, so your attitude can make a difference. Yes, there are some officers out there who are full of themselves but these are also the ones you have the least chance of winning an argument with and the highest likelyhood that they will rack up the charges if you get in their face.
You have the right to read the ticket before signing it. I'm not sure if this is true in every jurisdiction, but in the tri-state area around here, signing the ticket is just acknowledgement that you understand the charges and have the right to appear in court or to waive your court appearance and pay the fine. In every case I have encountered signing the ticket is not an admission of guilt.
If you feel that the officer is wrong or that the penalties are excessive, you can appear in traffic court and state your case. Again, attitude and record are everything. Judges have even wider discretion than officers and can drop or alter charges and set the fine anywhere between the minimum and maximum allowed.
It is legal for you to video an officer during the stop but it is in your best interest to do so unobtrusively rather than in a confrontational manner. Set the camera or your phone on the dash where it will capture what is needed and just let it run. Remember, the officer is likely also video taping or at least recording you as well and that record will follow you to court. If you are the one being hostile and confrontational, kiss any chance of a reduction in fine goodbye.
Judges don't like having their time wasted, by you or the officer. While it might not happen in open court, I know that some officers have been admonished by judges or department superiors for writing excessively punative citations or citations that are not adequately based in the law.