I just came from the beach, shirtless with my wife and infant in the car, the last thing I would do, especially after the beach is "race" anyone or drive "reckless". The other guy wasn't even "racing or driving reckless" the only thing the other guy could have been guilty of is speeding. I was doing 65 exactly and had my GPS to back it up. Cop is crooked. Even my lawyer was outraged and felt he shouldn't even be on the force...
I won't weigh in on whether i think you're guilty of the offenses or not, but it's probably not a good thing that you admit to traveling above the speed limit. Although speeding is not in and of itself determinative of recklessness, it is certainly a factor to be considered.
The main issue in all reckless cases is the mens rea of "reckless." as with all criminal cases, the mens rea is usually one of the most difficult things for a prosecutor to prove. here, the statute looks at whether the driver was operating a vehicle "recklessly in disregard of the safety of persons or property." Since this is a judgment call on the officer's part, it would be very difficult for you to go after the HPD on this issue.
what really sucks is that, because 291-2 is a petty misdemeanor, it was probably recommended that you retained counsel. I'm not sure what the rates are anymore, but i think that it used to be around $1,500 to $2,000 to retain counsel for a case like this. I'd hate to be out that kind of cash simply because the officer, in his opinion, believed you to be driving recklessly.
in regards to the other issue that you brought up, the American Bar Association's Model Rules of Professional Conduct places certain greater responsibilities on prosecutors. the model rules were substantively adopted by Hawaii, but Hawaii uses a slightly older and slightly modified version of these rules. Specifically Rule 3.8 requires a prosector to disclose evidence that tends to exonerate or exculpate a defendant.
if you feel like sharing your video with the prosecutor's office, you might be able to help the other guy out. at the same time, if there is incriminating evidence on there related to your case, it is possible that there are negative consequences for you too.