I agree with the video that you won't get over-penetration. I'm dubious as to how much penetration there will be at all. When you expand the center of mass of a rotating object, your rotational kinetic energy will increase.
Here's the problem I see. Rotational kinetic energy is given the equation: KE(rotational) = 1/2 * I * w^2
The problem with this is the rotational inertia, I, with most of your mass toward the outside is greater, but your rotational velocity stays about the same. Now, if we have some of the linear kinetic energy getting transferred to rotational kinetic energy, we will not get nearly the same penetration as a regular round, because the linear kinetic energy that drives the round straight is being taken away to both expand the round and to increase the rotational kinetic energy. In laymen's terms, if the round's linear kinetic energy is reduced to increase the rotational kinetic energy, which must happen to do what this round is doing, the overall linear speed of the bullet will slow down dramatically. This will cause much less penetration.
I don’t know about you folks, but I want my self-defense round to go in, expand and do damage. I don’t want to hit multiple areas of the attacker’s body and not have great penetration. I’ll need to see some ballistic tests on this before I would ever become comfortable with this round. Also, if you reduce each piece of the bullet by 1/3 (3 pieces) then each piece will not have as much inertia (measured by mass) to penetrate. They say it will curve through water based materials, like flesh, but it seems like it would stop dead when going through thick clothing.
My other question is, if you miss with this round, like they are saying you will with other rounds, I see the very real possibility of hitting more than one person with one round of these. It seems the round is LESS controllable than a regular round. Each piece of the bullet is 7" off center (the radius of it is 7" to give a 14" diameter hit). Therefore, if you more likely to not be on target with your first shot, like the manufacturer purports, then this shot will miss by an additional 7"????? This doesn't seem smart at all.