Whats happening in that clip is he is killing mr Softee,He was an ex mercenary i think + they used to call him Mr Softee because he drove an ice Cream truck around+ sold ice cream to kids, He was like Kuklinski's mentor + taught him how to kill in a bunch of different ways including,
cyanide, which is what he took from him + sprayed up his nose after he shot him.
Kuklinski killed some people by putting cyanide in a drink + then spilling it on a person + it would soak thru the skin + kill the person,+ cyanide doesn't show up in autopsies if they are not looking specifically for it,possibly not at all.
So he would just see his target bump into them spill his drink on them + walk away basically unnoticed + the guy would die shortly after + by then he would be gone + nobody even suspected him.
Mr Softee taught him that.
Kuklinski liked mr softee too,but once he mentioned his family,mr Softee was a gonner, he kept his family life to himself + his killing + shady friends etc. totally seperate from his family, he killed 1 or 2 other people who mentioned his family in a threat against him also.
Kuklinski claims over 100 kills,between his own killings + killing for the mafia.
If you like true crime ,the book is interesting reading,