Create this old-school ball effect for enemies & weapons?

They say a picture is worth a thousand words ... i'm looking to achieve this effect where enemies & some projectiles are made up of balls connected to each other.

https://youtu.be/43VliN72xWY?t=13s

How do I achieve this effect for the boss's bullets?

Are you talking about the first boss there?

If yes then I dont think the balls are connected.

It is just that the fire rate and speed is aligned with the refresh rate

There is an illusion of being connected but im pretty sure it is actually a series single projectiles firing out.