The larger format bottles have much thicker glass up at the neck, making sabering really difficult. It appears that his first strike was roughly proper technique, although awkward given the bottle size and the fact that he couldn’t be holding it. It did chip out a chunk of the glass, but not enough to get the cork to fly and certainly not the full ring with cork in it, which is what you really want when you saber. That’s where things went bad. The largest thing I’ve ever sabered was a 3L of Chartogne Taillet. It took three tries to get it open. Oafish, but no loss of Champagne and no harm to anyone present. I’ve had one bottle break in an unexpected way, which I attributed to a defect in the glass. That resulted in loss of 1/3 of the wine but no other harm.
Cheers,
fred