Why do the red and blue balloon explode in two entirely different ways? In this video the red balloon snaps in slo-mo at around 1 minute and 48 seconds. But in the same video, the blue balloon snaps in slow-mo, at around 3 minutes and 20 seconds in an entirely different way than the red balloon. What can be the cause of this different behavior in exploding? Does the weakest point of the balloon surface, where the explosion starts, follows the path of least resistance, which is different in both cases?
 A: Your question is answered by the APS Physics Focus article Two Modes of Balloon Bursting Revealed, 
30 October 2015, published in Physical Review Letters 115, 184301 as Popping Balloons: A Case Study of Dynamical Fragmentation. The two modes shown in the following images exactly match those seen in the Slow-Mo video (upper blue, lower red) :

The Physics Focus article summarises : 

At low pressures, a single crack can dissipate the stress, but above a threshold pressure, multiple cracks are required.

The Abstract to the article in Physics Review Letters explains more fully :

...Fragmentation processes involve large strain rates and short time scales that take place during crack nucleation and propagation. ... Bursting a highly stretched membrane yields a treelike fragmentation network that originates at a single seed crack, followed by successive crack tip-splitting events. We show that a dynamic instability drives this branching mechanism. Fragmentation occurs when the crack tip speed attains a critical velocity for which tip splitting becomes the sole available mechanism of releasing the stored elastic energy. 

