Fly the battery until the voltage gets too low. A lot of "nicer" (read $$$) have low voltage cutoffs that I suspect are not being utilized for him. He also may not be selecting a battery with the correct C rating. 2200mAh batts are not always created equal. If he is just grabbing one from the "charged" drawer without looking at the proper C rating that may also do it. Trying to pull more amps from a battery that just cannot supply it will puff it every time. Maybe there is something else?
None of my lipo's have an LVC, although most of my ESC's do. Josh is either not setting it or is just flying past it into the low voltage death range for lipos(under 3 volts per cell). He has said many times, he just loves to fly!
I do not take mine for any endurance runs until I get a few timed flights with a particular setup to judge safe flight times. Batteries are one of the most expensive single components on the model, I always try to take good care of mine.
It's the amp draw that's doing it. The battery chemistry can only support so man amps before it has problems. That's why higher amp draw batteries (higher C rating) are more expensive. When Josh is hot ridding on a speed plane or throwing bigger motors on things he doesn't always necessarily get a better battery and it puffs. It doesn't mean the battery is useless, often times they can be reused many more times but its something to be very careful with. Now there's puffed where it got warm and I shouldn't do that again, and there's puffed where its trash. It's a judgement call.