Because of the volatility, Li packs have to have really good thermal/current protection built in - so (nowadaze) they are pretty good that way. The vid I posted impressed me with the pack being used that many times pretty close together - I wouldn't have been totally surprised if it had shut itself down on thermal protection. I don't have too many occasions that I want to start 15+ engines at one time, but that kind of performance matters to me if I'm diagnosing a starting problem.
My buddy has a Mac booster pack (lead-acid) at his commercial shop. It's been beaten on pretty hard, but is still hanging in there.
That Mac pack won't start a problem diesel (meaning light truck, it'll likely do a vw tdi ok) in the dead of winter on it's own though. For that, I prefer another truck (high o/p alternator) with good jumper cables.
These Li packs seem pretty useful for many applications... Christmas is coming, maybe some TBN'ers will find one under their tree !
Nice for mobile electronics too - good option for charging a phone if the car dies, blows a cig lighter (er, excuse me... "12v power point") fuse, etc....
Rgds, D.