1) She was stopped and that's why I used my horn
Your video suggests otherwise.
3) It is not illegal and even the cop admitted that.
It is illegal. I just cited the traffic law that prohibits it. I've interacted with several police officers—in Illinois, no less—that were mistaken about what the traffic laws actually say.
4) The events in this video resulted in a new sign being placed at those intersections in that area.
Such does not contradict my assertion. The amount of road rage you're exhibiting, I'm quite certain, exceeds the amount of safety granted by that new sign.
3. Blaring your horn at a driver is illegal. You broke the law by doing that. According to ILCS 5/12-601(a), the only legally permitted use of your horn is "when reasonably necessary to insure safe operation". Venting your frustration at how someone else is driving does not fall within those legal parameters.
3) It is not illegal and even the cop admitted that.
But you fought the ticket the officer did give you. If that violation you got the ticket for was an illegal traffic action, why didn't you just pay the fine, or go to court, plead guilty, and pay the fine?
I guess there's a limit as to what you agreed with the cop about.
His ticket wasn't even for blaring his horn. It was for improper lane usage. I didn't notice any improper lane usage in his video.