I've probably played around with cord elasticity more than most - it's not that it gives less control, nothing
gives control (you have to
take control) it's just that it adds another variable to the equation which makes it seem unpredictable until you understand it better.
Basically, the cord stretches when you swing hard. Because I've not got a hard, aggressive style, the stretch is more a gradual ebb and flow - for someone who really hits a move like Matt, that elasticity is more pronounced. Also the weight of the sticks makes a big difference - I've usually strung my light-weight graphites with elastic cord (or straight-up elastic

) which again minimizes the effects.
I
might spring for some ColeCord if I get around to buying some new poi, which I've been planning to do for a while.