That I would not do because it would instantly trigger an escalation that would end badly.
Car had lights... I would assume he's plainclothes.
The one thing you should NEVER EVER do with either a cop or an armed individual:
Anything that does not go the cop's way is an instant provocation, regardless of how you might see it. In today's hypercharged environment, doing ANYTHING other than keeping your hands in plain sight, responding to questions calmly and following instructions might get you shot.
Haven't watched this with sound (at work) but it looks like the rider did it exactly right. Keep the encounter as calm as possible and take action after the fact.
PS: The cop is holding the pistol that way because he's trained to. Keeps the suspect from grabbing it.
PPS: Video caption mentions "deadly force" which is incorrect. Deadly force means firing the weapon, not presenting it.