A slaughterbot obviously needs melee weapons and needs to be athletic. Ballistic platforms are probably far more effective, but it doesn't send the right message.
2) current drones already have 4 tiny knives (blades). Enough to make it slightly larger/sharper and/or from titanium instead of plastic. That's enough to cut your throat or wrist and let you bleed to death ...
3) ... cover those blades with some venom or poison for "extra efficiency"
4) ... they probably don't even need some bullet - enough to detect your eye and stab you with a nail covered with venom/poison
I doubt you would have any chance with just a dozen of slaughterbots.
edit: formatting
Drones are extremely loud, especially those that fly that fast and small. If you have finely mashed net or large piece of cloth, drone already get into trouble.
Slaughterbots could carry a small explosive, just like in the video. Doesn't have to be melee.