Not standing up for the officer, but did find this statute per Utah law:
http://le.utah.gov/~code/TITLE41/htm/41_04012.htm 41-6a-209.
Obedience to peace officer or other traffic controllers -- Speeding in construction zones. (1) A person may not willfully fail or willfully refuse to comply with any lawful order or direction of a:
(a) peace officer;
(b) firefighter;
(c) flagger at a highway construction or maintenance site using devices and procedures conforming to the standards adopted under Section 41-6a-301; or
(d) uniformed adult school crossing guard invested by law with authority to direct, control, or regulate traffic.
(2) (a) If a person commits a speeding violation in a highway construction or maintenance site where workers are present, the court shall impose a fine for the offense that is at least double the fine in the uniform recommended fine schedule established under Section 76-3-301.5.
(b) The highway construction or maintenance site under Subsection (2)(a) shall be clearly marked and have signs posted that warn of the doubled fine.
Yet, in the vid, the cop tells the other cop that when the guy refused to sign, he said, "That's fine.", as if that part was no big deal. He seems to base his justification on the man's behavior, i.e., getting out of his car and walking toward the officer's vehicle. If I understand what happened after the watching the vid, the man was wanting to see exactly how fast he was speeding, and that he was actually in the 40 MPH zone and speeding when the cop first pulled him over.
Am going back to watch this again. Am not sure if the officer was trying to arrest him before the guy got out of his car or after.
Have yet to find a Utah statute that states a speeding ticket must be signed, but would guess that when a Utah officer requests your signature, there would be expected obedience to the officer.
Not once did the guy appear to be a threat, IMO, but am not a police officer, so I have no real idea how they perceive situations.