You can do it with Shape Layers (Strokes), but it looks like a tedious and time consuming task. It looks has been "handmade". I'm pretty sure the it's not made with any plugin.
Ahhhh aint creativity grand? As Jose said it's probably not done with any "effect" or plugin.
Based on their reel I'd say they put alot of time and work into it. And I highly doubt it was even done in after effects.
Probably done with a full featured particle system. Alot of that particular reel looks similar to high end work I've seen
that's being done with the latest Houdini tech.
In fact i think this studio is who did the recent chemical brothers video which I saw a breakdown of somewhere and it was in fact done with houdini. So they are doing some cutting edge work with that software.
So my guess is that this was achieved with some advanced particle systems using some sort of set goals for particle driven curves.
And I'd be surprised if I were right and it was that simple.
In other words...it's pretty advanced work. About as advanced as it gets & coming from some of the most talented people in the industry.
Maybe if you shoot them an email they'll accommodate your curiosity.
Here are some blog posts from them....Like i thought, in the most basic sense it was all done in 3d applications using procedural systems to drive geometry.