The tinsel lead is hooked to a coil homie..you have a rearword / back traveling EMF shooting back up the wire of the coil from the magnet being 'switched' and the cone moving back up.. Then the amplifier gates on the fets are telling it to go back down..when it's trying to go back up, and heat starts building up in the leads when the gates are switching at X frequency of the mosfets in the output stage. This is a combination of the EMF trying to go out of the coil, through the tinsel leads, and back into the amplifier...and the amplifier trying to tell everything to go back the other way. It crashes in the tinsel leads and that is where the stress point is, from movement, to heat, to high frequency noise, to EMF. There's a whole host of issues all popping up at the exact same spot and if it all lines up the same way it glows and explodes.
You see an ice cube here, the coil around the ice cube is the exact same thing as the coil that is inside of the motor of the speaker..there's no difference there.