It's not 90k lumens, it's 60something tops.
These chinese led arrays and not efficient enough to produce 90lm/watt. Plus those crappy chinese drivers he's using probably aren't running them at full power anyway.
By his own narration stating he gets about 10 minutes of runtime I'm estimating he's running them at about 65% power, because his 177 watt/hr battery pack would run a 1000watt led load, including a generous 80% efficiency for the boost converters, for ~6 and a half minutes.
The datasheet for those led modules shows 8500lm output typical for ~120w input. if you de-rate this you get about 8500 * .83 =7000lm @ 100watt
If you derate this further for his estimated input you get somewhere around 4500lm per module, or ~45,000 lumens total, and this isn't even factoring in the appreciable lumen loss from the light traveling through an inch thick glass aspheric lens.