The black male leans forward, revealing his intention to attack as his posture has shifted to load up the punch. The white male immediately clinches and falls to the ground, pulling the other with him. He is obviously very confident on the ground and does not mind which position he initially ends up in, as long as it is on the ground.
The black male grabs the other in a head lock, which is a terrible idea against an experienced grappler as it allows them to take the back.
Others intervene for a second but the fight eventually ends with the white male threatening to destroy the leg of the black male, which is not a hollow threat as he is holding a heel hook.
Rather than reaching for the knife when it is drawn as many people tend to do, this security guard punches the man, and as they go to the ground he and controls the hand holding the knife. He extends the hand away from the body which prevents the man from reaching for it with the other hand. Bystanders step in and assist. Excellent instincts.
Police officer attempts to take down resisting suspect with armbar, a technique commonly taught to police in many countries. This results in the officer failing to control the body of the suspect, and falling beneath him into a dangerous position. Luckily his colleague was competent and timely with the TASER.
Two men argue with two security guards. Another guard grabs one of the men around the neck from behind. As the other man looks back and is distracted, a security guard standing in front of him punches.
The guards flanked and overwhelmed the two men. Human only have eyes in one side of their head, and a split second of distraction is all that is needed to land a punch undefended.
Reluctant to go hands-on, police use their baton, then Taser which fails multiple times. One police officer attempts to knock over the man by rushing at him from behind but ultimately loses control as he stands up. The Taser is used again, then OC spray before the Taser is used once more before the man is taken into custody.
All of the tools police used in this instance depend on pain compliance, apart from the Taser which incapacitates for mere seconds IF the two prongs make contact correctly and in the correct positions on the body. Physical control with grappling techniques may have resulted in a faster and safer arrest, however these officers either lack those skills or were not willing to go hands-on.